You need to identify a couple of items
1. Is it Fios, Cable, or DSL
2. What is the actual speed upload & download
3. What will you use it for? Do you need speed?
Fios is the fastest and there is a neverending debate about dsl vs cable. Dsl comes in 768kb (we did not care for the 768K, too slow for us), 1.5mb & 3.0mb(fastest) (at least through my former provider) and it is an individual connection that is not split up between neighbors.
Cable in my area had 3.0 and I think 5.0 but it is shared between neighbors and got slow when everyone was home (evenings & weekends) most of the time it wasnt an issue. Occasionally on a snow day or whatever it would be really slow.
Fios came in 15 and 50mbs I think? Something ridiculously fast. We never had a single speed issue on fios, it was super fast all the time.
What will you be using it for? For general internet use any would prob be fine (I'd skip the 768K dsl) but anything else you wont notice much of a difference. if you work from home or download a lot you might want to get the fastest.
We preferred the 3.0 dsl to the higher speed cable, fios blew them both out of the water.
In my area ATT is not a provider so I am not sure if they are dsl or cable in your area.