I think your best option is to go with the otterbox for the best protection possible, but maybe you are hesitant because it required more effort to put on? Other than that, I think Incase slider would also offer good protection, but personally I dont like the concept of sliding my phone against the hard plastic case. SwitchEasy rebel is also nice in terms of protection, but again that might not be for everyone consider the vibrant design of the case.
I think iSkin solo is a nice case, when comparing with the SE colours or S Pixelskin. But if it was between the only two you have talked about in the title of your post, I would say pixleskin would be better, just because it has the most padding (though it is not protecting the screen cracking... only otterbox will do that, that I am aware of, unless I guess you go with some leather cases (i.e. vaja) with a flap on it)