for starters, its a 90 degree V, which means from a design/engineerng standpoint it has perfect primary balance. The higher you rev it, the smoother it runs. Then there is the whole simplicity thing. I liek simple things. And the handling, of course. Three basic engines since 1965. Round fin bigblocks, square fin big blocks, and smallblocks (Thats changed now with some of the new OHC engines, of course).
Only real explanation I can give is, to just go spend a day on one. NO ride less than 500 miles before an opinion can be formed.