Verizon or AT&T, which is better?

I've had Verizon for about 2 years now, and my contract is coming to an end. While I like the coverage and the fast internet, I find that they're customer service sucks and they're quite expensive. So I was thinking about switching to AT&T because I've heard they have much better customer service but I've also heard they don't have as good of coverage. Would it be worth switching to them? (I'm wanting the iPhone plan, if that makes a difference).

Many people are concerned about dropped calls, if you live in the city and there's less power cell towers, then verizon could be better

I'm with AT&T. I've never had a problem with dropped calls. Their coverage is pretty good, especially if you're in bigger city (I'm in San Diego). Their 4glte network is faster and in areas where lte is not available they usually have HSPA+ (like 3.5g). It's like enhanced 3G (6mpbs download was typical). Their 3g is also much better than Verizons 3g (1 to 2 Mbps download). Verizon's only benefit is better overall 4glte coverage.