Well if you had to choose between the PS 95 and PS 90, I would recommend the PS 95. This is because going from 10.4 oz to 12.6 oz is a huge jump, as is 100 to 90. You would be going from a lighter tweener to a heavy player's racket.
For the PS 95:
10.4 -> 11.5
100 -> 95
"The trouble with me is that every match I play against five opponents: umpire, crowd, ball boys, court, and myself."-Goran Ivanišević