What I consider to be best isn't necessarily the sharpest. Focal length, AF speed, image reproduction etc... are all factors I'd consider when coming up with said list of best lenses (that I've used personally, I'm sure there are others but I've not had the opportunity to use them... such as Student's Leicas). So, mine are...
EF 17-40/4L - Reasonably affordable, good wide angle zoom. Would have been beaten by the 20-35/2.8L if not for its faster AF.
EF 35/1.4L - Superb all round standard lens on a DSLR. Great available light capability.
EF 400/4 DO - A very nice balance between a supertele (with IS) and weight.