the issue with the AR10 is it's not a totally universal platform like the AR15. So lots of parts are not interchangeable, so once you go with a system you'll want to stick with it (or just keep the rifle stock as it came from the manufacturer in many cases).
LMT MARS-H is a great system if you want to be able to swap barrels and calibers around easily (not cheaply however).
PWS makes a long stroke piston system that is good if you are going to shoot suppressed, but has some proprietary parts (piston system). But they can be great shooters.
DD is easy to find locally, and always a solid choice. Lanxang is also a local/atlanta company that makes some very very good 308/6.5 rifles that are worth a look. JP is probably the best known for accuracy if that is your main consideration. Lots of options out there, most are very well made.
If you can find the parts build. I built my AR15 and spent 1/2 of what basically the identical gun from a well know manufacturer would charge and I had zero wait time. Even if you but a complete upper and lower kit or something you can normally save.