My personal recommendation would be Xenon
Personally I would recommend most of the current Cygnus Knights (Mihile excluded) for the sake of accessibility and saving you ms mesos later in your 4th job. However, I had a similar experience to yours when I started playing this game. A friend recommended me to start with Aran, a choice I still have yet to regret but as time went on I found myself choosing for my own and deciding what my best class would be. Moral of the story, just play for a while and any one class will stick; they’re all balanced (for the most part.)
My personal recommendation would be Xenon, very agile with an array of attacks. 3rd job is rough to some mild extent, but like every class 4th job is where the sheer power comes in.
Another recommendation would be Paladin, even though their made of titanium their damage is pretty low to compensate. For me it’s cathartic to play my Paladin and seeing all the damage be 1-100 compared to my other classes that take mostly normal damage.
Shade is also really good, little amount of buffs (mostly passives) and pretty straightforward overall. The only thing to keep in mind is the story, but I won’t spoil it for your surprise if you so choose!
I’m also currently trying out a Hayato, but since I haven’t gotten too far my opinion has not been solidified yet. I’ll just say now though they’re a mp eater, but they have very fast attacks with a bit of linking skills here and there.
Kaiser is the epitome of pure redundant for me, mostly using one attack throughout your leveling, and just doesn’t feel satisfying at all. (For me at least) I don’t know if you’re too interested, but Dawn Warrior are FAR better than Kaisers honestly!
Angelic Busters are glass cannons, they dish out incredibly high damage, have a really high damage cap compared to most classes, however they really can’t take a beating to easily, but they do have some utility to keep themselves alive easier than most classes.