Welcome to FT! You'll find lots of disagreement, but many (including me) would argue that American is best for domestic upgrades. As denver suggested, though, more info from you will generate more info from folks trying to help you out.

By the way, for more answers you might want to delete your question here and post the same question on the Miles Buzz forum, which is more appropriate for the information you're seeking. (You can't delete the entire post, but by editing it you can remove the words. I suggest doing this because otherwise you'll be committing the FT no-no of posting the same question in two different forums.)

Come to think of it, moderators, might you move this to Miles Buzz?