I don't remember Eric being as good offensively as Timonen (though it's close), but I remember him being better defensively. It's a really close thing, I don't think I'd fault anybody for having one over the other.
Pronger/Howe, that's interesting. I'd go with Howe as well. He had far more impact considering he played a lot longer than Pronger did with Philly. And Howe at his best in Philly, from the games I've watched, was something to behold. I've only seen a fairly small number of those games but Howe struck me as being better than Pronger when he was a Flyer, chiefly because his skating was incredible. The Flyers could look like two totally different teams when he was on the ice vs when he was off. Of course, my frame of reference is small for Howe though, so it's not terribly reliable. But in those games he's easily one of the best players I've watched in the O&B. I'd put him in Clarke/Bernie/Lindros territory, but a step below them. His stat line from 85-86 is stupid-good.