Is that not a dumb question?
There are some many flavors taht you can't pick just one. Whit if you find 25 best versions? Are the all best at the same time?
The look and fell varies. That is by design.
Change the question to 'What are a ome of nthe better Desktop Environments for Linux
But click here if you want The Most Poupalr Linux.
Bear in mind that the above links are now already dated. Really, even one of the distros made of a year ago can be the best for you if it meets your needs. Still, both links above are useful for anyone thinking of trying something else.
My question is: Why are some people switching to Fedora? What does it have?