I'm mostly a studded felt fan. Studs help a lot, but they can go on felt or rubber just the same.
From a traction perspective, it really depends on what surface you are talking about! Felt really sucks in mud, silt, and snow. Rubber sucks on big freakin slimy rocks. Some rubbers are better but I haven't seen one that compares to felt.
Gravel, well, everything's good on gravel.
I think everyone is pretty much telling the truth on what has the best traction for them. It just varies where they are fishing. Not a difference of opinion, a difference of REALITY. Then we get in these debates and everyone ignores the fact that we're all basing our opinions on uncomparable situations.
That said, if you prefer rubber for the environmental aspect, and not the traction, there's nothing wrong with that. If you prefer felt, that's fine by me, but for all of us, please be careful about the spread of invasives. Wash and dry your gear appropriately.