If you're interested in a 29er, my advice would be full suspension with around 110-130mm of travel in the rear, 120-140mm of travel up front. Peter has the CS-FS29 available at xmcarbonspeed.com.
However, if you're like me, and your willing to try something new, either a FS 27.5+ or a 29+, I have one of each and have not looked back. I had x-country oriented Chiners and while they were really good, once I started riding plus bikes, I enjoy riding more than ever. It's up to you but if you're building a new bike, give Plus a try.
Carbon_Dude, for starters thank you. I've enjoyed reading a ton of your post in various threads since I've discovered these boards. I have never ridden a 27.5 but still love my 26 and have thought a bit about how a 27.5+ may be a good landing spot between what I have. If I drilled on my 26 I am sure my skill set for things like a manual would improve and on a 29 its a lot harder for me to bunny hop and doing the most basic of skills. I've been watching a ton of videos between the two sizes and thinking about the trails I ride and my skill set. Would you say the FS29 is more of a trail bike vs a XC? Do you know what this frame is based off of?
I don't much about the FS29 but i'm pretty sure the CS-821 is based off the older Scott Spark and the M06 is similar to the Yeti ASR with a little more travel. The biggest difference between the two is the M06 having a solid rear triangle as compared to a pivot. To me i would think it would make the rear feel a little more stable and also work the shock differently. I'm still deciding which would benefit me and my riding style/conditions more.
Thanks again! That is tough between the two for sure, I've been watching the build threads with the M06.
I am trying not to over analyze as I am sure at my skill it may not make a huge difference between the frames but hoping to get what will be a nice upgrade from what I have.