Well it all comes down to what you enjoy playing more.

For me, I started the game as a mnk. I enjoyed that job a lot and still do. After a while I started leveling brd and liked it a lot so I kept playong it and got i90 / 80 set. Then after that I felt like trying war because I love how thier AF gear looks and also because i was kind of sick of DF waiting time for brd. I've mained war since then and enjoyed playing it a lot. I have an i100/90 set for him while the brd stayed at i90 and mnk was left at i80-ish.

A couple of days ago I felt like I missed my mnk and wanted to play it again. I Switched to it. Got most of hos i90 gear and now I'm thinking of maining him again. It's what I enjoy playing the most at the moment so why wouldn't I? And might also get the animus for him and not for war after all the atma grinding.

I guess what i'm trying to say is: play what you enjoy the most and if you think some time in the future that you enjoy a different job more, then switch to it. As long as you're having fun.