The Sennheisers are great as far as durability - I throw my HD-280s in a backpack when I'm on the move and they haven't broken. I know someone who owns the HD-555s and does the same thing. I'd strongly recommend the sennheisers - What you'll get is a very neutral headphone with great sounding mids and highs. If you're a big fan of the beats you'll find the senns anemic in the bass department because they won't have as much as a kick as you're used to.
I'd say the Klipsch S4is - To be honest I haven't heard them but I have heard a few beats products and don't like them at all - Way too much emphasis on bass and not enough on highs and mids for my liking. So largely because of that I'd say the Klipsch ones because I hear their sound signature is more mid and high friendly. I will say this though, if you're a basshead get the beats.