The 120-300 f2.8. While this is a rather large and heavy lens, I have used it extensively for my sports/action shooting on my Canon 1-series cameras. It is essentially a very good 300/2.8, but you get the added bonus of the shorter focal lengths in the zoom. It is easier to handle than the Canon 300/2.8L, and stopped down to f3.5 or so, it is every bit as sharp, from what I have seen.
Also have the 150 f2.8 macro, and find that to be an absolutely outstanding lens also. While the AF is not quite as snappy as some others, it is very accurate. The sharpness of that lens, even wide open is impressive, and the 150mm focal length is a nice compromise for macro work with flowers and bugs.
My 12-24 f4.5-5.6, or whatever that one is, does an excellent job for most of my superwide needs on the Canon 1-series. I got lucky and have a good copy. It does not really come into really good image quality until f8 or so, but wide open it will do a decent job for most DSLR work. It is amazingly rectilinear, and with careful compositions, one can get some very nice images. It remains in my bag the most of all lenses, as when I want wide and sharp, I grab the M8 ;-)
LJ