Archer would of been boring as hell, ESPECIALLY during those tight VS's or when you're chasing some guy that thinks he's almost gotten away, just to see me behind him and baam, he's toast ^^
I instead made sure people couldn't z on my party when we were getting close to an opponent party or town, I could carry the leadership mark and make sure people couldn't spot us from far, I could also MAKE USE of the leadership mark and draw people to me so that my party could get away when it was required, and the list goes on and on.
That's one of the reasons why I stayed sin aswell, the things I could do to keep my party safe were endless, and lets face it.. SIN is the god-class, you just need to train a lot to reach that point in which you can contribute something to every stage of a battle, no matter what the outcome.
PS. You really should see my SS folders, the things I've done is freaking hillarious and awesome, things only sins could do and no other class could even get close to.
Edit: Because if I were an archer, you wouldn't have something to look at xD >>>>>