If you could meet the characters and hang out with them
I think if any of us met Spock (usually everybody's favorite character), we would realize that he's not somebody we'd want to be around. We'd probably be real irritated with his aloofness and coldly analytical mind, and the fact that we couldn't joke around with him. It's easy to see why McCoy gets mad at him.
McCoy on the other hand would probably be a great guy to be around if you were just relaxing in the lounge playing a game of checkers or cards of something. And if you were one of his patients he'd probably treat you real well.
Kirk would also be okay to be around unless he had his mind on various problems with the ship or Starfleet. He would probably be quite irritable if he was worried about his ship or his crew. Additionally, you probably wouldn't want him around your wife or girlfriend.
I don't think I'd like Scotty. He'd probably be one of those guys who tells you how everything works. Sure, he can back it up, but if you don't know him, you don't know that, and it gets annoying regardless.
Uhura seems like a nice down to earth person. But we saw so little of her personality that there could be some kind of bad trait there, lurking under the surface.
Sulu is okay but I think I'd get tired of him jumping on whatever the latest fad is (fencing, botany, etc). I always got the feeling he couldn't think for himself.
And Chekov. I wouldn't want to be around him. He's kind of a buffoon who wants to tell you how everything was created/discovered in Russia.
So ultimately I'd want to hang out with McCoy the most.