The only gunners I know are in FFTA and FFX-2. They're quite recent.

But to answer the original question, I usually make Aeris a White Mage. (SPOILER)Then she dies. So I get angry and go "Screw you! She was my best character other than Cloud!" and start throwing random pieces of furniture at the TV. I also make Red XIII a Black Mage cuz his physical attacks are kinda crap. Barret is always full physical. No magic for him. I usually stick my summoning materia on Cloud (Cuz he's groovy). The others (That I use) have a bit of everything.