3 grouops would be enough for me
Buffers > bd sws tanks dwarfs summoners(?) > dd
Hmm maybe split dd with aoe and dd without aoe like daggers and pr, but pr has fc and daggers can lure so its not very big difference
Any dd is easy to level. With supports is harder because some people have boxes and dont want you in party. Tbh i think everything is easy to level up, unless you want to solo farm / are new to l2 / dont know how to make your own party that benefit you most.