My standard zoom for the 5D2 is the EF 24-105/4L. The favorite prime is now the normal Voigtländer Ultron 40/2 but at the other end the narrow EF 200/2.8 is superb. At 2.8 its shallow depth of focus is spectacular as is its sharpness, even wide open. As it is fairly small and completely black it does not attract attention the way a white EF 70-200 barrel would.
I’d sooner sell the EF 24-105/4L than the EF 200/2.8! It’s a keeper!
Sometimes I find it very versatile and keep it on for days on end, but usually the Ultron 40/2 gets a go in between.
Some shots with no internal order or apertures: