I would also say now, that it is the Canon 5D MkII. But I concur that lenses are much more important. I shoot with a 40D but have invested in quality lenses.

Canon 1D would also be up there – but the 5D is just so much more competitive now.

5d or 5d Mark II

Although, I personally shoot with the 40d and spend money on the lenses. If you want to see what the 40d can do please check out my work:

best? or most used?

most used would be canon or nikon somethings

best would be hassleblad