RE: Not an assault rifle!
AS far as BEST bang for the buck IMO the Rock River would be hard to beat. IMO, when you buy a colt, you're paying for the name more so than paying for best bang for the buck. Les Baer is custom, again, great rifle with accuracy garauntee, but not necassarily the best bang for the buck. Bushmaster and Armalite are good rifles for the money. Heck, even DPMS makes good stuff for the money.
The biggest problem that you'll run into right now is not paying too much. With the current very high demand for these rifles comes a higher than normal cost for them. IF you can find any of them made by the makers listed in this post for $1000. or less, in new condition, you've found a smokin' deal.
I've got two custom builts that I use to hunt predators with. Not long ago, I didn't see a need or have a desire to own and use them for hunting. BUT after I got to borrow an AR-10 Armalite from a buddy while calling coyotes, I soon realized the benefits of the quick follow up shots. I even plan on using my AR-243 wssm. to hunt antelope this fall. These days, the AR style rifles can be just as accurate as most off the shelf bolt guns and in the predator hunting worl, they have become very popular, with even Remington making thier own version in the R-15 and R-25.
Good luck with finding one that you like at the right price.