Well @filmjunkie08 is right, there are just so many of them out there that choosing the best is really tough to do. It also certainly depends on the person and what they are using it for, so you have to factor that in. All I know is that I am perfectly happy with my Samsung Galaxy and I have had no issues with it, so for that I am content and do not plan on changing anytime soon.
I agree with DiscountDreams. Since gadgets upgrade frequently, the "best" smartphone is always temporary according to what model is currently out. But brand wise, I would go for Samsung or Sony.
The one that has arrived in the market recently is the best smartphone. Until Sansung 6 had not arrived samsung 5 was the best smartphone for Android users and once Samsung 6 arrived, Samsung 5 was no more best smartphone. Th new best smartphone was Samsung 6. I think Samsung and Sony have bets smartphones.