I've been doing a ton of reading on phones recently. I just got the new Samsung Galaxy SII. I bought before the announcement that the iPhone would be available on Sprint. I wanted to stay with Sprint because I wanted the unlimitted data plan they have. I am loving my droid based phone, but I've never owned an iPhone. Used one a couple of times.
Anyhow, a lot of stuff has already been said, but I'll try to put it all together.
As stated previously, Apple tends to build great products and back them up well. In both the Mac and phone world, you have to pay more for that quality and attention to detail. That's not to say you can't get a quality droid. Someone mentioned that the processors are faster on the droids on the top end. Wait, that was you. That's only partially true. You can get Droids with higher clocked processors, but that doesn't mean they are faster. A lot goes into CPU architecture. A great example is the current intel X86 chips are clocked way lower than some previous version but are way faster per core. The Apple 4s is probably faster than any current droid. The GPU (the thing that processes graphics) is way faster on the iphone. You have to wonder why some droid makers don't switch to what Apple is putting in the iPhone. The iPhone cannot do flash. If you think you are going to be viewing a lot of flash content, that pretty much eliminates the iphone. The camera on the iphone basically kicks every droids butt. They basically brought it to really good point and shoot level or even low end DSLR on this rev. Siri on the new iphone is interesting and makes the phone far more friendly. Droid has had a lot of the same functionality built in for a while. Siri just jumped them in overall useability, but you can still do things on the droid like hit one button and say "How deep is the Grand Canyon" and it will automatically do a google search and give you a list of hits. Or you can say "Text wife I'm running late period can you pick up the kids question mark?" and it will set up a text correctly and you just have to touch send. The screens available on the droids are significantly bigger if that's what you want. However, the display on the iphone is better than almost any current droid. One final consideration is that I believe this week, Android will be releasing their next OS (Ice cream sunday or something like that) and the Nexus Prime or Prime or some such phone will be announced which will leap frog all current droids (even my very well received Galaxy S II).
You mentioned 4g. The iphone does not support 4g (basically, they are waiting for the 4g radio to be built into the chip and that won't happen for 6 or 8 months). 4g uses a ton of battery in the current off chip radio. However, it's really freakin fast and if you think you are going to be doing a lot of streaming or downloading, it's basically the difference between DSL and dial up. I leave my 4g off 95% of the time, but if I need to download an app, it's at least 5 times faster to turn on 4g, wait for the connection and then download. If you intead to download a lot where you don't have access to wifi, this could be another deal breaker for the iphone.
I upgraded to my first smart phone a month ago, but my wife needs to upgrade and we'll certainly look at the iphone as well as some droids and see what she likes best.
Don't get too caught up in all the fan boy stuff. You really can't go wrong with a top of the line Droid or the new iPhone. Play with them a bit and get what is most comfortable and intuitive for you. You'll be happy either way.