I have owned and used iPad, iPad2, Xoom, Transformer.
Scoring from 0 to 10, with 10 being the best.
iPad gets an 9
iPad2 gets a 10
Xoom gets a 6.5
Transformer gets a 7
Love my iPad2 and don't see giving it up anytime soon.
I may be biased due to the fact I have the ipod touch which I carry...