I would say decide what you want to hunt for before creating another character, then decide what class would do the best job of completing that hunt. In general, hunters are good at ep1, rangers are good at ep2 and forces are good at ep4. Of course all classes can handle all areas in the game with the proper gear and experience.
It may also be a good idea to look ahead at what events are coming up and prepare a class to hunt for an upcoming event item, because they're worth quite a bit and you can only get them once a year.
For me, the best FOrce ID is Oran hands down, purplenum is pretty nice too (especially if you want to hunt psycho wand). A lot of people mention pinkal, but the only good drops are wedding dress (which a FO would stuggle to find solo) and Mother Garb+ which is honestly a bit overrated.
For hunter, Whitill is always nice and I've enjoyed Bluefull.
For ranger, whitill, purplenum, and yellowboze.
Don't forgot about greenill. It's good for hunting materials which will make your characters much stronger. Greenill is fine for any class, but I would say it's better on Forces and Rangers.