Im not sure if there is a "best" AR on the market. I think most of your major manufacturers make pretty good quality rifles and parts. You just gotta find one that's built and configured the way you like it. I will say that some of the top tier rifle makers do put a little more effort into fit & finish. However, I don't think you'll see a huge difference in terms of rifle performance. As far as the Bushmaster/Windham Arms, I'm sure the new company is just using the same factory/tooling as the old Bushmasters. As long as they have some experienced people there, I'd be willing to bet the quality is on par with the old Bushmasters. I would look for some online reviews - if others say the quality is there, I wouldn't hesitate to buy one.