The iPhone OS (or iOS now) is definitely the better, smoother, seamless user experience right now. Android does have some work to do, but I believe it will get there. But you also have to remember that iOS only runs on iProducts. It is very much proprietary software. And Android, especially running with Sense, does have a lot of features (home screen widgets!) that iOS lacks and is in desperate need of.
As far as hardware, well it seems like Apple was working maybe a little too much on their software because in my view, they're a little behind right now. Not to say they don't have secret prototypes behind the curtain that may boggle the mind. I am very happy with the EVO itself. Camera (both of them), screen (size! and look), and overall size (not too bulky for something as big).
The biggest selling point was probably the WiFi Hotspot feature, especially since Sprint is not capping their data plans, like AT&T is doing now. Plus, it's an actual WiFi Hotspot, not just phone tethering over USB or Bluetooth.
Also, I'm hoping to see 4G in my area soon (greater Los Angeles) and take advantage of that, which is supposed to happen by the end of the year. When AT&T rolls out it's LTE network, no luck for the iPhone 4.
All in all, I am happy I made the switch to Sprint and the EVO. I have had each of the iPhones so far (even waited in line for hours for them), and I just wasn't impressed enough with the latest. Now, I will be waiting to see what Apple comes up with next .. and I might just have to switch back, but the mobile phone market is starting to get pretty hot!