This was a rigged question when I posted it, of course
After all, how do you define best? But the safest answer is probably the M&P/Model 10. It is the most successful (and I'm pretty sure) widely-produced revolver (and maybe handgun of any kind) of all time.
All of the other wonderful guns that have been mentioned, the 27, the 29, the 19, etc., all sprang from this original masterpiece.