Personally, I like Instacast. John Gruber has recommended Castro, which I haven't tried. Instacast seems to do exactly what I want. It downloads my subscriptions in the background, doesn't bother me, and let me have a button for 2 minute fast forward jumps. It isn't perfect, and I think it was expensive $3 or $4. Having said that, I've been tempted by other apps and never pulled the trigger because it works well for me.
I had tried Downcast. It's quite nice too, but it didn't work quite as well (for me)