I just got a powerscreamer and they recommend either the ibanez ac-109, boss psa-120 or digitech ps200r. anybody had to get one these? which is best?

you don't HAVE to use one of those adaptors with those pedals, they just say that to make more money

find a cheaper one you can use daisy chains with
if you have more than one pedal, or plan on getting more in the future, look into something like the one spot. i personally dont have one, but my room mate swears by his. it powers multiple pedals and it should work with most kinds. definatly something that you should check out as it beats buying a new adapter for each pedal you buy.