I have played most of the classes to an extent across the four seperate times I've given the game a shot. At my longest run, I decided (having played every other class at this point) that I really wanted to give the Death Knight a try. Since the other class that I seemed to enjoy was a Rogue, I rolled a Blood Elf and played this rogue, mostly entirely alone, up to level 55. It was a lonely, terrible time.
At 55, I jumped into a Blood Elf DK and managed to make my way to 73. Then, the entire group of people who had campaigned for months to get me to play dropped out of the game, robbing any reason to try and press through to see the so called "good" content at the end.
Of all the classes I played, I probably enjoyed the DK the most and seemed to suit my play style. I caught a lot of flack for playing as one, which I don't quite understand, and I was informed in no uncertain terms that I was not welcome in most parties because my class didn't have a "point".