What do you look out for when main-ing a character/class/job?

1) Uses gear i already have. Putting so much effort into pirate %str and then switching to anything else is a horrifying experience. Only two classes in the game use this type of gear. Luckily they're both classes that are interesting and now viable.
2) Viable in bosses, but not boring to train.
3) Underdog.
4) Not squishy.