There are good AR-10's and there are bad ones, there are good DPMS LR308's and there are bad ones. As for a head to head test of reliability, you are not going to get a magic answer here. Both do very well and every once in a while you get a piece of shit...yes both Armalite and DPMS honor there warranties and will fix it if you get a piece of shit. As for accuracy they are only as accurate as the shooter. If we are taking just straight carbines, They are probably equal, it you are talking target models then they are probably equal. I own a DPMS LR308, it had a problem with the chamber when I got it, DPMS fixed it in a heart beat, then it ran like a champ...The AR-10 my bud let me borrow, took 3 trips to the range to finally get all the bugs worked out and the thing working in the 95% reliability range.
If you are going to buy one it is going to come down to personal preference. You just need to pick options and look at cost and make the choice, one isolated review of the "head to head" is not going to mean shit in the long run.
If it was me I would get the DPMS due to the interchangeability with AR-15 parts and they are priced more reasonably, as well as the SR-25 mag usage.
Matt