PPSC encourages playing for the strong second. I think this makes the game far less interesting. There's often little or no incentive for large powers to stop a solo from happening, thus more easy solos happen. The minor powers have little leverage to work into a draw if there's no real threat of throwing the solo.
This is really quite an old and polarizing topic. It comes up fairly often on the forum. I think I conducted the first ever "+1 poll" (see
threadID=791962) where WTA won by over a 2-1 margin.
Here is what Allan Calhamer, the creator of the game, thought about this topic:
http://www.diplom.org/~diparch/resources/calhamer/objectives.htm
He gives a balanced treatment, entertaining both ideas, but ultimately it seems that he is arguing in favor of WTA.