Definitely lightning, cid raines, and yuffie. Papalymo is an excellent fire mage to dive too and I recommend him. Avoid like the plague Delita and Luneth's dives for now. If you had Luneth's USB I would've said otherwise. Krile has a terrible dive, her LMR1 and LMR2 are much better. Relm is worth considering if you are doing magicite. Her LM2 has bonus resist buff and her dive keeps her alive with the extra HP and stats. Alphinaud I think you'd need his USB to make his dive worthwhile.