I don't really have favorite type of guy... I guess the seiyuu is very important as well. I'm often biased because of that xD
Hum, hum... (Be serious, myself !) Let's say that it depends on how the guy fall in love with the heroine. When it's too sudden, the story is strange. I really like to see how the relationship is created, deepened. In the end, it depends on the story itself. For exemple, I was stunned when suddenly, in Sangokushi Rensenki, the most serious guys (Bunjaku & Unchou) fell in love with the heroine. I was like, "Um... okay... ? What happened in your head, hmm ?"
But well, if I should tell you the ones I hate, it would be
1) yandere (because it's scary)
2) playboy or popular guy (it's sweet but I guess I felt bored since it's the same almost everywhere)
3) hetare (the only exception is Shinnosuke from GHP ! May I be biased to KENN's voice... ? xD)