I like using both but really, melee is just better, easier to break, rarely if ever backfires (stupid charm status) and is mainly just hastle-free in Tactics. As opposed to magic which has to factor a magic stat, Faith, and the faith and magic stats of your enemies, requires a charge time which makes anything past the -Ra spells completely impractical, dealing with MP, weather, andyou have to be careful with positioning so the enemy doesn't just walk up to the mage, smack the mage and then watch as your Fire 2 spell finishes him off after taking off a third of the enemies health, and leaving you down one guy...

As oppose to a Knight who can take quite a bit of damage, can deflect several attacks with a shield and does awesome damage, or a Monk, who can use Earth Rend and Aurablast, as well as Chakra and Revive for white mage duty. Even the Chemist is more practical than a white mage cause his actions are immediate, don't miss cause the guy has low faith, and frankly has better range.

Mages are not terrible, but they require much more planning to make them useful and oftentimes, the melee class have similar abilities with no MP cost and don't have to deal with several factors like the mages do. I still love using mages, but an all mage team versus a melee team, I'm betting the melee will destroy them. The melee are just fully ready for ass kicking right out of the box, and tinkering with them only makes them more lethal.