In the past, I would say I went for Jack-of-all-Trades types but as I got older, I started to appreciate more defined roles for each character so I go that route when I can. In games with actual Job systems I tend to to have at least one mage class and one strict melee fighter with the third/fourth changing depending on my needs or if I wanted to check out a particular class.

The only entries I don't really do this for are VII and VIII cause the lacks of variety in major skills, especially in the early game, makes it difficult to stick to defined roles that are fun to play as. In games like FFII, I go in with a plan on how to build my party.

It's funny you bring this up cause I've been playing SaGa Frontier 2 which like FFII gives you characters who start in certain roles, but can be made into anything you want, yet it's more fun to stick to their starting classes for me, especially considering how mage heavy this game can be.

In retrospect, while I love me some Job System, I've come to realize that I tend to like RPGs that give me characters with per-determined roles better than games that let you build anything.