I have never once had a problem with ATT and I have had them for over five years.
It costs a bit more to have them yes. But I like to get a new phone every year or so and not pay outright for it.
Straight talk is okay but you obviously have to buy your phone outright and no one is going to pay 600 bucks for a phone and then have to go to walmart to buy phone cards to keep it activated. Plus, unless you have some sort of aftermarket insurance on it then you better walk on eggshells with your expensive phone. Because if it breaks, you are out a good deal of money on top of the money it costs to buy another one of equal value.
I like the fact that ATT covers my phone should something happen too it, because I have had to make insurance claims a few times and they always have a new phone at my door in two days, tops. Around where I live they have awesome service.
On top of it, they have decent customer service. And sadly I cannot even say close to that about Straight Talk. After my ATT contract expired I contemplated switching to straight talk. What a mistake. I called them to order a sim to put into my ATT android and they charged me not once not twice, but three times for ONE sim card! I got charged 150 bucks for one sim card. I called them, and after talking on the phone for a collective total of 10 hours with people who could barely speak English I got my money back (in 3-5 business days of course). I will never use a company that does that to their customers.
I like the big phone companies for the ease of use, the updated technology and the fast networks. Straight talk uses ATT towers, but their network is not nearly as fast.
If you are not a person that uses their phone for a lot of purposes, you could easily get by with straight talk. However, I use my phone daily in college and at work for everything from business contacts to statistical analysis of run time reports. A speedy network and updated technology is a must for me. If you only use your phone for making calls, sending texts and browsing the net a little bit then straight talk is okay. If you can get passed their CSAs that are sitting half way across the world and the fact that if you break a phone you are out of money and have to buy a new one out of your own pocket.