I agree with BreakerDave, do you have a specific feature like accuarcy or durability that is most important? Is there a price limit?
I have a DSA FAL that built like a tank and is very dependable, I wouldn't expect it to win any accuracy contests but with the right ammo the groups are very respectable. Even better than I was expecting. You said "top of the line" and this isn't that, but it is relatively inexpensive and easy to find accesories and parts for, so as an all around 308 rifle it's a good choice in my opinion.
I've read posts from several people on different forums about the DPMS and other 308 rifles on the AR15/AR10 design and the majority seem very pleased with them. I would like to have one as well if it was piston driven. I'm not sure if the Panther is piston now or not. I need to check into that.
But my choice of a "top of the line" kick butt semi-auto 308 would be the M25 White Feather with it's Krieger barrel. There are other custom M1A rifle makers out there but the White Feather would get my vote.
A Smith Enterprises Crazy Horse would be cool too.