Disclaimer: I've not played FF 1-3 so you won't see any from there.

Knight - FFXII TZA Job, god that game has a crazy Knight.
Archer - FFX Wakka, he counts fight me.
White Mage - FFVII Aerith, for her limit breaks mostly.
Black Mage - FFIX Vivi, love that little guy and his nukes.
Thief - FFX Rikku, come now.
Monk - FFVI Sabin, such a great skillset.
Machinist - FFVI Edgar, he has an actual variety of great and useful Tools.
Ninja - FFV Job, Dual Wield and Throw are so good.
Samurai - FFX-2 Dressphere, just a lot of fun to play with.
Dancer - FFV Job, sorry X-2 Songstress but this FFV job is just broken good.
Bard - FFX-2 Songstress Dressphere, this one you get though, your Sing is better than your Dance anyways.
Dragoon - FFIV Kain, can't go wrong with him.
Dark Knight - FFX-2 Dressphere, it fits too well.
Berserker - FFX-2 Dressphere, look I know they're supposed to just Berserk, but hell if I don't enjoy a Berserker with actual variety in moves. Plus it has Evade & Counter.
Time Mage - FFVIII Ultimecia, because if she don't count who does. Well, second choice would be the FFV Job though.
Blue Mage - FFVII Enemy Skill Materia, still reigns supreme. Although it's really dumb OP, admittedly.
Freelancer - FFV Job, still can't help but love how obscenely powerful it gets.
Summoner - FFX Yuna, because aeons.