I don't have a certain favourite because my lenses serve different purposes and they cannot replace each other. My most used lenses are the 14-24mm and PC-E 24mm. Probably use them about 80% of the time.
mazeppa26 said:haha seems like a lot of people likes a few specific lens...
it'd be good if we can take some time to say why that particular lens is well liked/favourite, then perhpas it will be more educational for ppl reading this thread who's looking to upgrade/change to another lens
my camera has only one len : Canon EF 24-70mm f/2.8L USM
it is my favourite .hehe