THIS ARM BAND will hold the iPhone and the iPhone in a few select smaller cases.
THIS ARM BAND will hold the iPhone in ANY case i've thrown at it (Lifeproof, Mophie +, OtterBox .. to name a few).
I have both but mainly use the bigger (second) one because I use the Mophie Juice Pack + .. a lot. Don't let the pictures fool you, it isn't *THAT* big .. I find it good sized. Even has internal pockets for a key or other smaller items.
I have a SPIBelt as well .. and it is nice, but if you take the phone out a lot while running (to see distance/time/pace or anything else) .. it can be annoying. Having said that, I do use my SPIBelt a good bit and sometimes even for the iPhone.