Thinking about an AR10

[BPTactical]

Buy a complete rifle for the reasons you mentioned-mix masters suck.
You didn’t lay out a budget- that will define what is worth looking at.
You basically have 3 patterns to choose from:
Armalite B series- the originator of the platform. Great rifles but limited magazine (M-14 modified) availability- I am not 100% sure if anybody has made a successful copy.
Knights Armament SR25- the gold standard along with the LMT rifles-$$$$$. They run great and use standard mags but proprietary parts. I’m not sure if anybody makes an affordable variant.
DPMS Gen1 pattern- probably your best bet and clearly the most prevalent of the large frame AR’s. This is what the majority of makers rifles are patterned after. Most parts interchange to a degree.
Stay away from the G2 DPMS- unicorn parts as mentioned.

Smith and Wesson M&P 10’s are solid rifles and won’t break the bank, the CMMG MK IV is decent- the Aero is decent if you can find a factory complete rifle.
Not impressed with Palmettos PA-10 at all- clearly a budget rifle.

Budget in a Superlative Arms adjustable gas block- it can go a long way to cure an ill running rifle.