I don't care, because water bottles are consumable items.

• Elita One 27.2mm seatpost: I've bought like 5 of these for various builds. Hard to recommend much else. Light, well-made, can handle a load, no branding. https://www.aliexpress.us/item/3256805646314200.html
• Faceted anodized top cap: Well made, nice bit of bling on a bike with an appropriate color scheme. I have the rainbow one on my Tarmac and it's been complemented more than once. https://www.aliexpress.us/item/3256805632252290.html
• Reflective tape: I put some on the rims of my commuter bike for side-on visibility and it works great. Cheap and adheres well and is VERY reflective. https://www.aliexpress.us/item/3256804860946991.html
• Cyclami TPU tube: I use these for my commuter bike where I don't want to bother with tubeless. In the 27.5 size they hold air very well. The rear tube suffered a small tear (not puncture) as I was installing a new set of tires, but I patched it with one of the included patches and it hasn't bothered me since. https://www.aliexpress.us/item/3256805483094623.html
• ZTTO P3 hubs: I've built 3 wheelsets with these hubs, they're my favorite cheap hubs. They roll well and have good weather sealing. The measurements in the listing are accurate for wheelbuilding. Not super light but not egregiously heavy either. Of note is that 12mm front thru axles will need an axle reducer (https://www.aliexpress.us/item/2251832711018601.html) and the front endcaps will probably need to be filed down to accommodate the shallower dropout cutouts. https://www.aliexpress.us/item/3256802437891171.html
• Kalloy UNO stems: I have versions of these on all my bikes. Light, cheap, strong.
• XCADEY chainrings: I don't have much time on these rings but chainrings tend not to change very much over time so I feel comfortable recommending these. They shift very well (50/34 at least), are light enough, and imo look pretty good. https://www.aliexpress.us/item/3256803817933289.html
• RYET 3D printed saddle: tried one on my road bike and liked it enough I got another one for my gravel bike. The shape is basically a copy of the PRO stealth which works well for me. The claimed weight is accurate and the construction quality is excellent. https://www.aliexpress.us/item/3256805023659024.html
• PASS QUEST jockey wheels: a nice little upgrade from most stock pulley wheels. Durable, narrow-wide, with good bearings - sealed, not the crappy ceramic bearings completely exposed to the elements that most Aliexpress jockey wheels have. https://www.aliexpress.us/item/3256801862899014.html
• Spcycle MTB handlebars: generic carbon MTB handlebars, but very well-made with a clean interior. Plenty strong, I've taken these down some real jarring singletrack with no issue. https://www.aliexpress.us/item/2251832093175674.html
• ZTTO nipple wrench: the little mickey mouse ears are so comfortable to use. By far my favorite nipple wrench, better than the Park Tool one I was using. https://www.aliexpress.us/item/2251832816974319.html
• DECKAS 1x chainring: I've used 4 of these on various 1x setups and they work great. So cheap too. I wish the branding was slightly more subtle but it's not terrible as is. https://www.aliexpress.us/item/3256801606393029.html
• Generic flared gravel handlebars: Shockingly durable and comfortable. I like that the come in narrower widths. The internal routing is clean but not very wide - fitting shifter housing + brake hose through each side was a royal pain. Unfortunately the underside isn't really shaped for external cable runs. https://www.aliexpress.us/item/3256802785082557.html
• Flyxii FE-02 gravel bike frame: a real tank of a gravel frame. I love mine. https://www.aliexpress.us/item/3256802462426945.html
• SERAPH road handlebars: my favorite road handlebars ever. Such a nice shape, well-made, light and stiff, nice channel on the underside for clean and easy cable routing. I hope they never go out of production. https://www.aliexpress.us/item/2255800581774460.html

• Generic front light: I think this is the same one sold by "Offbondage" (lol) and a few other stores, but this one doesn't have branding which is why I went for it specifically. Nice and bright with a flashing mode, has a good bar mount, USB C charging. https://www.aliexpress.us/item/3256804897699962.html
• OG EVKIN HB010: good shape, reasonably light, external cable routing for easy setup. I have this bar on my commuter and it works well. Only reason I don't rate it higher is because the first one I had snapped when my bike fell over in its stand - can't really fault it for that but my other carbon bars have survived their bikes tipping over. https://www.aliexpress.us/item/3256805458531947.html
• Generic bike baskets: I use 2 of these on the front rack of my commuter for light but bulky cargo loads. Not super well-made but they do the job and fold down for storage off the bike. https://www.aliexpress.us/item/3256805376389581.html
• Sunshine cassettes: I've had 3 of these; 2 11-speed (11-36 and 11-42) and one 12-speed (11-46). They shift fine, not quite as good as Shimano but that's to be expected. Very heavy though. https://www.aliexpress.us/item/3256803959318100.html
• AVID HS1 brake rotors (definitely copies): 6-bolt only, but they don't warp because they're thick, they brake well, and they're incredibly cheap. https://www.aliexpress.us/item/2251832609689188.html
• Nipple holder: makes the process of lacing a wheel much nicer. For 3 bucks, well worth it. https://www.aliexpress.us/item/3256802890581426.html
• ZRACE Blade MTB crankset: simple fitment and steel axle, same as Shimano hollowtec cranks. Reasonably light, graphics aren't too obtrusive and the included chainring is surprisingly good. I have found that it creaks a bit when it gets dirty but it's so easy to pop off and clean that this isn't a major issue. https://www.aliexpress.us/item/2255800868849020.html
• Spcycle M05 frame: size medium in glossy red color came in at 877 grams - amazing! Despite the weight, it's been a very solid hardtail for my not-very-extreme needs. Only drawback is the rear driveside dropout is too thick for the stock hanger so I had to file down the hanger to make room. https://www.aliexpress.us/item/3256802796251755.html

• TOSEEK 143 saddle: the shape works fine for me. The construction quality is decent but the middle unsupported section tends to sag a bit too much imo. https://www.aliexpress.us/item/3256805099852978.html
• ZTTO MTB cassette: shifts ok, not nearly as good as the Deore cassette I was using on my previous MTB groupset. But this cassette is amazingly light, the claimed weights are accurate, and I think at least some of the shifting issues I have are down to some derailleur hanger issues on my MTB frame. https://www.aliexpress.us/item/2255800094553452.html
• IIIPro centerlock disc rotors: they don't warp which was a major improvement on the Dura-Ace rotors I was using, but after about 500 miles they developed a squeal I couldn't get rid of even with brake cleaner and sanding their surface. Swapped to Campy Ekar rotors and have been very very pleased with them. https://www.aliexpress.us/item/3256804105057808.html
• ZRACE Hardrock crankset: I've used two of these. One has lived on my gravel bike for 1,500 miles, has been beaten up, fully submerged multiple times, been put through singletrack riding and 1200 watt sprints, and is basically brand new. The other one had the axle and driveside crankarm separate and develop play within 100 miles on my commuter where it never saw any abuse. So... ymmv. https://www.aliexpress.us/item/2252799820023948.html

• Ridenow TPU tube: I only use these as backup tubes on my road bike. The one time I had to use it, I was riding close to home with a friend and he punctured with no spare tube, so I threw this in his tire and it flatted within 5 minutes. Fortunately I was able to ride home and bring him a butyl tube! I tried patching it when I got home but it failed with 3 different patches.. So small and so light, but this really is an option of last resort in my saddle bag. https://www.aliexpress.us/item/3256803826508749.html
• Sensah SRX Pro: The shifting was very good, but the clutch on the derailleur was so weak that it dropped my chain several times a ride. I quickly replaced it with a Deore rear derailleur + JTek shiftmate which worked ok. The braking was ultimately the dealbreaker - see below - but I kept the shifters around on my commuter bike, paired with a SRAM Force 1x rear derailleur, and the shifting was great and the braking much better with rim brakes. https://www.aliexpress.us/item/3256802576089351.html

• Juintech F1 brake calipers: I just could never get these to brake all that well. I tried different pads, rotors, preload adjustment, etc etc etc; ultimately I was descending a notoriously steep and winding local road and I nearly lost all braking power, even after stopping and letting the system cool down for almost 10 minutes. I ordered 105 hydraulic shifters and brakes the next day and they're infintely better. Don't bother with these or other cable/hydro solutions, just go hydro. https://www.aliexpress.us/item/2255799928780428.html

I'm in need of new bottle cages so this interests me much...
do these carbon ones, recommended above, scratch the bottles? My only experience with carbon cages was one of those Bontrager XXX knock-offs, and while it held the bottle well it just left it all scratched, maybe because it was too tight, but I also believe it was a case of rough edges on the carbon.
I moved to Elite Cannibal bottle cages, the nylon one which is already pretty good at <30g each, but the price on these ones right now is just insane, at least here in Brazil.

Another one I was interested is this Xoss N2 one in nylon, seems pretty good price/weight relation

Maybe too late but I (and my GF) have these on our bikes. Maybe 14 in total? All have been flawless.

Yes, on the order page where you have to enter the coupon code.
But it took a LOT of tries  I had a couple of times that it worked, but after clicking the order button it said some items were out of stock, so I had to play around with the items in my cart to finally get it working...

but always the same, or did you vary?

according to this list: https://www.reddit.com/r/Aliexpress/comments/17sqdld/discount_codes_for_singles_day/ there are different codes for the same discount values