The "which is faster" debate is so debatable it's basically useless to try and figure out.
Good DSL will have slightly lower latency than a good cable modem connection. DSL bandwidth is generally asymmetric: that is, you have much more downstream bandwidth (web surfing, downloading files, etc.) than upstream bandwidth (sending files to friends, running a server of any kind, etc.). Cable modems are the same way but even moreso. With cable you generally will get way more downstream bandwidth but you get capped at 128kbps upstream (~16KB/sec). Cable modems share bandwidth with your neighbors...but at the same time many DSL providers also share the bandwidth just at a different point in their network. This means that if you live in a heavy cable modem using area (like I do), your neighbor's can affect your net connection at heavy usage times.
Either one is going to be way faster than AOL over dialup. The quick and easy answer from me is: get a cable modem if your area offers them. DSL setup can be a huge nightmare as many, many user reports on dslreports.com will attest to. DSL is better if you want to run your own servers from home but to get the higher bandwidth DSLs you're going to have to pay a lot more for the service.
Cable modem service generally runs around $40-50/month while DSL runs from around $40-200+/month depending on what grade/type of DSL you get (average consumer runs $40-60/month usually).
Gaidin