A lot of it depends on what you want out of the phone. Ease of use. IPhone will be simple, but you will be limited by the slower 3g data speeds, unless you live in a non 4g area then being stuck with 3g isn't going to matter. 4g is very speedy, but dependent on your carrier ( Verizon, ATT, TMobile, etc) the speeds may not be much faster than 3g. Also, if you aren't going to be surfing Jazzfanz from your phone it won't matter anyway.
Battery life is another thing. 4g especially verizons Lte is a battery eater. So you may want to look at phones with larger battery capacity or extended battery options. The RAZR maxx is very good for battery life.
If you like to tinker with your phone ( rooting) and want to always have the newest updates and latest operating system then the Galaxy Nexus is the phone you want (what I own). Other phones can be rooted and modded as we'll, but generally Motorola phones have a locked boot loader, meaning they are not very mod friendly. Samsung is very easy to mod as well as most of the HTC phones. Beware the Verizon Galaxy S3 has a locked boot loader (Samsung has now offered a developer version that is unlocked, but you have to buy from Samsung).
Basically what it comes down to is what you want to do with your phone. The phones of today have more proccesing, memory and storage than what most computers had 10 years ago, so your getting a lot of technology in a somewhat small package. I've gotten to the point of not using my actual computer more than once or twice a week (I'm typing this reply from my Moto Xoom, a tablet).
If you are at the end of a contract, you may want to look at few of the prepaid plans as well. Even though you will have to purchase a phone outright and pay more, in the end you will save money. When our family plan ends we will no longer be chained to Verizon. The rates just keep going higher. We have two smart phones, and two other basic phones on our plan, get a discount due to my wife's Gov job and still.l pay close to 200 bucks a month, Vzw charges for the plan, then an extra 10 bucks per phone, plus another 30 bucks per smart phone for the data plan (whicn is the lowest, it goes up from the 30 a month, just depends on the amount of data you want. I get 4gbs for my 30 bucks, wife gets 2gb). So as you can see, there is a lot to consider when buying a smartphone.
Sorry for the long winded reply. Hopefully it may be of some help.
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