So, I've been planning my next ink order and questioning which type I should buy. I'm pretty settled on the rubber-based at the moment, because it seems more opaque to me - oil-based seems just a little more translucent, and maybe it's my imagination, but with my oil inks, it looked like there was some minute seeping around the edges of my prints. Again, maybe I'm just imagining it though - I'm not sure. From some of the discussions I've seen online, it sounds like both are equally good, but everyone has their own individual preference.
I did find the oil-based to be easier to clean-up than the rubber-based - but I don't know that this should be the determining factor in my work.