Iphone 4 or HTC Inspire 4G?

Which is better? (AT&T Service.) I have an iPod touch 4G so would an iPhone 4 be worth it? Would I find the iPhone exciting or just my iPod as a phone? I want the iPhone 4 Because I found an awesome case for it. If I were to go with the iPhone I would get the Speck Candy Shell Case is Moon Sicle White whereas if I went with the HTC Inspire I would get an Otter Box Defender Series Case. Respond ASAP please! Thanks! (: **I will be choosing a "Best Answer!"**