So I did some research on classes and stuff, and I like support type classes in every game I play.

I'm looking for the most fun support that is also needed often for bossing/leveling.

Opinions/thoughts?

Beast tamer is rather glitchy, which is bad for an already unstable game.

Everyone loves Kannas and bishops. Kannas lose most of their value when it comes to bossing though.

Leveling. Kanna more than Bishop.
Bossing. Bishop more than those 2.
Link Skill. Beast Tamer.

Thats the gist of your list.
Leveling is Kanna because they pretty much double the spawn and make it almost impossible to empty the map if its big. All this class does it get to 3rd job. Spam 1 button in a safe spot. Done. AFK.
Bossing is Bishop because they got blesses/revives/heal and so on. Bosses now have a cooldown on potions. Active bossing role but people now can just solo unless they want to do crazy bosses.
Link Skill is Beast Tamer because they give boss % atk. No explanation. It's a link skill mule.

Grrrr. I think Beast Tamer was my favorite too, boooooooooo.

Bishop is a close second, but yeah.

Beast tamer isn't even fun.
Sure you have 4 animals. BUT!!! You have a set skill points that's the same as any other job and you choose where to put them across 4 different animals.
THINK OF THIS LIKE. You have all 3 mages in 1 character and their skills cannot be used at same time and if you want to use fire mage skills, you better have put skill points enough to use the 4th job skills AND if you want to use bishop. You better have enough skill points for that shit too. Meaning you cannot have all 3 unless you want 3 half complete jobs in 1 character