i have last year's westmark and it's a great board that can do everything pretty well. if you decide to go the freestyle route it'll be great; if you just go the freeride route it'll also handle well. it'll do a bit more than survive on sketchier terrain too. so yeah, if you only want to ever need one board that'll probably be it. you can still snag this for about $350 if you find it.
if you have bigger feet, i've heard good things about the blacklist (i think that was the name), which is the same board as the westmark but wider. reviews say that it rides even better though. can't really say much about that. this instructor i rode with got the revolver (wider version of the evo) even though he didn't need to because he felt it rode more "clean." but it only came out this year, so if you want one now expect to pay retail price for it (~$450).
only bad thing about arbor is that their durability seems suspect. i got my westmark last year and granted i ride really rough and i don't mind going over thin cover, taking closed trails, and i also live on the east coast, but it seems like the top sheet and the base seem more easily damaged. meanwhile, my friend rode his zeppelin for 4-5 years and it doesn't look that bad at all, and he rides just as rough as i do. i thought it was just me but seems like a few people share this opinion.