humm if u are mostly a stage player and made a battle eir something is wrong lol
and i think dain is the best for staging, he cam spam skill and kill mobs in no time, he is a mass destruction machine, i have one and killed daru in history at lvl15, cuz is very easy to ice wall and range enemys,
i vote eir in second just by the fact that u can get any party at any time if u are an eir everyone "need you" (N>healer - u dont see N>knight, wiz, tia very often lol) plus, be a suport eir is easy it is more about pay attention at the fight in a general way.
sieg is also good, but u have to know the tricks or you gonna suck, u need to know how to use, provoke, play dead, counter and side steps, combo is also a must or you gonna be raped by any high lvl mob, also if u wanna be a pro pvper sieg is the best.
i dunno about tias, never played they
but sure, play the one u like most =D