For me this is an extremely difficult question to answer, but I can tell you who some of my favorite characters are, however these are not in order or preference.
1. Deadpool (1990s Deadpool, is the best)
2. The Joker
3. The Mask (I mean the original, though the Jim Carrey movie was decent, it was too different from the comic)
4. She-Hulk (The Sensational series is just awesome)
For me a large part of what decides if I will enjoy the book, is if it is humorous as well as action-packed. What about the rest of you folks?