I would look for a Hybird case. It gives you the best of both worlds. I've dropped my phone countless times, not one crack or chip. I believe i found mine on boxwave. AND yes the iPhone will break! haha good luck
Selling it with the case, is probably a better value for the next owner of the phone(unless they already have a case). I wouldn't jail break it, that all depends on the next buyers preferences. You could jail break it, then find a buyer that didn't want the phone to be jail broken, then there...
I love Apple. But the new iPhone 6 may make me switch to A*****! I've gone over all the specs, nothing is to my liking. Unless the Apple "rumored" iWatch is bad***. I may just wait till Oct/Nov/Dec. for the Note 4, and finally make that switch.