Best tele lens under $600

I have some $$$ to spend and need your help.  I'm looking for a quality tele lens for my T2i.

Other than the Canon 70-200 f4 (non-IS) "L" lens, what might be some other contenders from other brands, with equal image quality?  (Or at least might close in IQ?)  Longer than 200mm would be a plus.  Thanks