I love my Canon 200mm f/2.8L II. It is cream city in bokeh, and it barely gets sharper as you stop down. It is also very well balanced...a trait that Canon seems to feel is entirely optional in their lens line-up.
Just starting a collection of alts, but my current fave is a humble Oly 50mm 1.8. Its got the right breeding for this particular type - silver nose, serial #, Japan made - but the characteristics that thrill a newbie like me are its deep contrasts and wonderful warm color. Its bokeh is a beautiful (to me) swirl, which is apparently a function of its narrow objective element. I now search pawn shops looking for the unrealized gems to add to my collection.
As far as having that unique look: Sigma 50 f/1.4. I've had a LOT of MF 50s, and the Sigma 50 has the best look of all of them, with AF as a nice bonus! Beautiful rendering.
The BEST AF lens I own, though, is likely the 70-200 f/4L IS...it's just phenomenal. Prime-like sharpness, wonderful color, fast, accurate AF and 4 stop IS. It's a gem. I also can't leave the Sigma 150 f/2.8 macro out of the discussion.....so there are a lot!
