If what you are searching for is Soloability, and wanted in teams youd be looking at those clases in this order:
Bladedancer, Abyss Walker(40+ Assasin), Archer.
Bladedancer: TEH partymachine of choise. There is not a singel party that would not go crazy over your dances, Nukers, Melees, Archers, Poles... heck even a giran craftingparty would want you for faster recharge! - Can also solo extreemly well and with the crit dance + focus swords... SS is cheaper then usual.
You get heavy armor master from lvl 20-40 as paulus knight. So you are proficient with heavy armor from that point. You also as DE get nice stuff like HEX!
Abyss Walker: My class actually, i love the daggerclasses. You migth wanna consider wich race you choose for dagger as DE are very good dagger (they all are) but lacks such skills as Fake Death, Lure. Try to find the dagger that has the skills you want in one. I choosed the DE dagger myself. You can party prett well as a dagger, prefferably with bladedancer/buffer in small groups. Solo is also very possible althou id argue the only real good melee soloer is Bladedancer and summoners. Avarage on both solo and party. More od a DD then support compared to Bladedancer.
The Archers: aaah... the 900 range w00t-i-got-buffs!-archers. Hate em or love em, they still hurt like monsters... buffed up to the skyes that is :p. As an archer buffed or not you will be looking at soloing for all lvls, or duos with any heavy buffer. No point for an archer to party with anything else then other archers and buffers couse 1 crit = aggro and a whole party glaring at you when all the melees have to chase the mobbs (god i loved teasing the slow gladiators when i played my archers by taking agro and kiting in catacombs). Monsters in soloability/duo. Very weak to bigger parties. And ofcourse notourious for their PvP ability when buffed.
NOTE: an unbuffed archer is as powerful as a dwarf ;)
Bladedancer: Party machine, very good soloability, support/DD
Dagger: good party, good solo, primary DD
Archer: Solo machine, loves buffers, primary DD
Hope that info helps you decide ;) ill gladely explain more about these classes if you got more questions.