V-necks all the way! Especially if you've got a nice chest/shoulders... May be surprising but too into the quadruple deep-v, especially if there's going to be chest hair poking out. Polos are good too.
Stripes are good for patterns, haven't really seen any other kinds that aren't incredibly tacky/obnoxious. Plain colours are fine; grey, burgundy, maybe some nice lighter blues/greens to be more appropriate for the spring. :P
I personally like crew neck cause the extra fabic tends to keep the upper portion of the shirt tighter and allowed the shirt to hug my shoulders more. I feel a bit too exposed (yeah the dude with shirtless pic), and feel as though the shirt becomes looser.
I think V-necks are more bold, and if you go that route, you should be going for a certain look. That's why I think they lend themselves to being different colors. I think dark purple V-necks look good for some reason. I only wear crew necks though.