I have both an AT&T and Verizon iPhone. Overall performance on both is comparable. Where one has bad coverage, the other generally has bad coverage as well. *228 option 2 is something CDMA users have to deal with. Unfortunately, it is important to keep the Preferred Roaming List (PRL) up to date.
Everyone's experience with the iPhone will be different. You can use the experience of other users, but keep in mind your unique circumstances will dominate. Your best bet is to take the iPhone for a test drive and use it as you would expect to. Use the old rule of thumb that as long as you are happy in the majority of places you need the device (home, work), that phone should meet your needs.