They can all be used in endgame and it's better to have a class you play well and enjoy than a slightly more in-demand class that you resent or are bored with. Go with what works. Test out your options. Change your mind. It's all fine.

Honestly, many classes play off each other. Leveling DRG forced me to think in terms of off-GCDs, which improved my BRD. Better rhythm and comfort with timing from BRD improved my BLM play to the point that I no longer hated it and picked it up as my second main.