I'm one that prefers the shape of the Oasis. I've never cared about buttons but I'm getting quite fond of the Oasis ones.
I like the concept of the split battery (assuming it worked reliably) but I think they went a little too far in reducing the battery in the Oasis itself.
I'm somewhat biased in favor of the Oasis anyway just because my Voyage screen is so bad. I hate that the screens on both models are such a lottery and now it looks like the batteries are a lottery too.