I recommend we add more classes, for more variety. For example.
Warrior
Black Mage
Red Mage
Thief (One I'd use)
Beast Master
Lancer
Archer
Binder
Spirit Mage
Spirit Monk
Ninja
Geomancer
Dark Knight
Shaman
Magic Archer
Gunner
Weapon Master
Priest
Talisman User
Battle Mage
Warlock
There are just a few suggestions. Another good thing that I would like, is custom races, it would add more character creation and customization. Therefore, it would be more interesting.
Some races you could add are:
Dwarf
Elf
Roegadyn
Lalafell
Orc
Dark Elf
Laguz
Beast men
Animorph
They are just suggestions. I don't expect you to add them in JUST because I asked or suggested them but it would be nice to see. I think it would make the Rp a lot more fun and interesting.
The entire point of doing an LH RP is to use the pre made world of LH and use it with minor adjustments to fit the RP.
What you're asking is more like another fantasy RP which uses LH as an inspiration. I personally feel that the classes would either break or not fit the game (like Gunner as LH doesn't have guns as a big one) and they aren't anything interesting too, all of them feel bland or generic or done already. Most of the classes you propose are already in LH as different styles a canon class can take. Most of these classes are more archtypical presets from other fantasy media and do nothing to advance or increase the depth of the RP/story. They look and sound pretty and all, but bells and whistles will only ever be bells and whistles instead of something useful.
Same story with the extra races, they seem frivolous to me and do nothing in reality to make it any much better than what canon races could do. The large majority of them are just additional bread and butter races of fantasy and Elves and Dwarves already exist.
If we're going to be doing a Log Horizon RP, then I think we stick to Log Horizon and not try to make another generic fantasy RP.