Secondly since the 177 has a lower stack than usual (for most people) you can consider ordering extra spacers just in case.
Watch out for the seatpost setback also with relative to toptube length and reach.

Good call. Thanks.

Will depend on where you live, but if you're happy with rim brakes, look at branded second hand bikes, you will get the most value out of those.

Thanks Serge,

For some context, I live on Waiheke Island in Auckland, NZ.  Lots of short, steep hills and rough chip-seal roads.  An ideal setup is tubeless, 28/32mm tyres and disc brakes. A gravel bike would be good here but not so good for races and sportives, which is what I train for.  I'm currently 1.87m and 100kg, so disc brakes would be handy, particularly on wet days.

I hear you on buying a second hand bike. It is something I have considered. My preferred action is going to be to build up a new disc brake bike for the reasons stated above, and put my existing rim-brake bike will on the trainer.  I'm really interested in the experience of building the bike and think I'd really enjoy it.

Also, just putting this out there as one of my considerations: While a steel bike gets to a certain point and doesn't fatigue anymore, my understanding is that carbon frames continue to fatigue as normal/abnormal load is applied over time, effectively leading to more give between the carbon layers and developing more flex.  Visually, I wouldn't be able to tell the difference but internally, the best days of the frame might be over. Now, a lot of the people that emphasize this are also people that are trying to sell you a new bike, so I'm not saying this is necessarily as big an issue as some people claim.

Equally, going for a branded frame does not guarantee quality. I previously watched this Hambini video trashing the quality of a BMC time machine frame: youtube.com/watch?v=UzjeCuA4hGc

Lastly, and please don't take this the wrong way as your comment is helpful; there is a little bit of irony about the fact that I'm on a forum about Chinese carbon frames and I'm being advised to get a second hand established brand frame  .

I am currently leaning towards the Dengfu R12 or the VB R-177.  Pricing currently seems to come out at $760 + free shipping for the R12 and $500 + $150 shipping ($650 total) for the R-177.  Both would seem to have good tyre clearance, and yes, the geometry is more towards the racier side than endurance. (Sorry, I'm just not ready to admit I'm no longer a racing bike rider).  The difference at the moment is that the claimed weight for frame+fork for the Velobuild is nearly 200g lighter than the R12 while also claiming a higher carbon modulus.

I'm told earlier in this thread that Dengfu is better quality, but if I look on their website, there are two very bad reviews that mention flex: https://www.dengfubike.com/collections/carbon-bike-frame/products/r12-disc-frame (I mean kudos to Denfu for not removing those reviews from their site but they are still a concern....). On paper, Velobuild looks like the way to go, and to be offering a stiffer, lighter frame, but then there are some comments on this thread challenging their claims, and there could equally be similar reviews that have been removed.

This clearly seems to be an area where there is a certain amount of risk (which I'm prepared to take on) and differences of opinion, but also one where you can get a real sense of achievement and learn a lot along the way.  For me it's about the journey as well as the bike. If I buy a dud, so be it. What do I do about it and what do I learn from it? I'd still like to minimise my chances of buying a dud though.

The 1056 or R12 will be much better built.  But you've also chosen 3 different bikes with different geo and tube profiles so you might want to think about that.

Thanks. Yes, admittedly, I'm not at all well versed on geometry and I did notice that the tubes seemed more geared towards weight savings in some and aero in others. 

I currently ride a 2011 S-works SL3 with R7000 105 components. Rim brake, obviously. It's on its way out and I'm not that happy about what you get for your money from the LBS these days, so want to build up my own bike. Not just for the cost savings, but also for the learning experience.  I thought I'd go with some frames that were similar to the SL7 but obviously I've missed the mark. I'm obviously many years older now, and I'm wondering if my reach has shortened a bit.  I'm also heavy enough that the weight savings from a very lightweight frame will be wasted on me. I'd rather go with a frame that is a bit heavier but well made and remains stiffer for longer.  I don't race apart from a couple of 160km sportive's per year, so happy to go with a more endurance type bike.

I know this is a very open-ended and question, but if you do have any suggestions about a frame that might be a good match, let me know. Thanks.

This one: http://www.velobuildmall.com/products/vb-r-077-ultra-light-road-racing-bike-frame-with-light-seatost-toray-t-1000-carbon-fiber-our-lightest-frame-ever

They tried to claim it was how they normally did it and that they didn't think people would remove the bearings (despite selling me a replacement bearing and bolt kit with the framesets and regularly selling them to others).

That's total BS. Anyone who knows anything about bikes knows that bearings can fail or that users may want to upgrade them.