i'd probably want to be Saber's master. for one thing, she's the coolest anime character i've seen in a loooooong time and i'm biased for Palladin class types (my main character in D2: LOD was a paladin). second in line would probably rider. she's yet another extremely cool character and again i'm biased for the assassin class type because that's my character class in RO (say what you want but i think she's more of an assassin type than kojiro and that true assassin guy).
if archer wasn't a guy, i'd probably pick that class to since he likes cleaning up and stuff (go servant and make yourself useful and earn your keep) :D hurray for boy butler. lolz
PS (i wasn't able to include Lancer in the poll options since there are only 6 slots. sorry about that)