Honestly, OP, I think trying all jobs to level 50 is a TERRIBLE idea. I'll explain why without taking up an entire page and making you read through a bunch of crap.

Simply: Jobs do NOT play anywhere remotely similar to the same way at level 50 as they do at level 95 and in Endgame. Period. Gaining experience in EXP amounts to knowing how to EXP really well. It doesn't amount to being able to perform the functions that jobs perform in Endgame well, because Endgame and EXP are not even remotely similar.

The best advice I can give you is to tell us what sort of job you want to play in Endgame, and then we can give you a better idea of what job you may want to try out. "EVERYONE IS GOOD AT EVERYTHING AND EVERYTHING IS GOOD AND YOU CAN'T TELL ME HOW TO PLAY" is just outdated tripe that doesn't actually do you any good. If you want to play a certain way and be effective at doing something in actual Endgame content, I can give you a decent recommendation of what job may be the best way of accomplishing that. Regardless, it's probably not Red Mage either way.