I think there is a AK-pattern Saiga in .308, although to be honest, I'm not much of an AK guy.
If you have experience with ARs and enjoy them, there are quite a few options out there. The only downside I am aware of is that there is no "standard" AR10, so quite a few of the parts (to include upper/lower receivers, mags, etc.,) are proprietary and interchangeability is spotty.
Do your homework and decide which brand you want to commit to.
I have an ArmaLite AR10, and like it pretty well. But ArmaLite makes an A and a B, and they are different. DPMS makes their pattern, and i think that one of the ArmaLite patterns matches that. Then there is PSA, which matches...something...maybe.
As I say, do your homework. Much like choosing a wife, changing your mind later will be messy and expensive.