I liked to use Aeris, mainly as my magic person but once she bit the dust, I remember replacing her with Cid. I'm pretty fond of all of the cast of 7 but I like Yuffie the most, even if she caused you the most trouble...never used poor Vincent though, just left him in the coffin to sleep for all eternity.
I find that I never use magic other than in Midgar, and that's only because i dont have the enemy skills/materia yet. Beta wipes the floor of everything, Mantra magic is a great hit all attack for the early part of the game while only requiring one slot (and can hit all more than once unlike a low level all materia). Lv 4 suicide works on a suprising amount of enemies and bosses too. I guess I use cure a little until i get white wind. White wind also removes all status effects so you dont need esuna or whatever. I generally use phoenix downs to raise anyone who dies in my team. You get a ton of those and x-potions on the way to wutai.
I realized after my last playthrough, I didnt use any of the summons except for choco mog a few times early on. The only one that got any AP really was that and Hades because it was linked to added effect.
Purple materia are the bestest.