After attending the gun show last week I've become interested in building a .308 gun. Help me decide. I built an AR on an Eagle Arms lower so I'm kinda partial to the Armalite. But I hear talk of differing mags between the two. Any input?

This is the golden age of 308 ARs, and you have at least 4 magazines to choose from:

Armalite AR-10 (previously based on M1A)
KAC/DPMS/POF/Fulton/LWRC/LaRue/JP/Jet/Tubb/Magpul/SI defense
G3
FAL used by RRA


But things get confusing after that, like if you get a G3 lower, then you can use a DPMS upper.   Or an Armalite uppper.    If you wanted to, you could do an Armalite upper on DPMS mag lower.   There are so many choices, people are getting it wrong and mixing incompatible pieces.

The Armalite magazines are a one manufacturer deal.    KAC/DPMS style mags are made by at least 6 manufacturers, with prices from $15 to $115.    

Whats better is a Ford / Chevy thing in my book....

Mixing DPMS and Armalite looks like total crap.  Just don't do it.  As far as the G3 mags are concerned, the CMMG lowers which accept them are designed to work with LR-308 uppers.