Cable or DSL.. that's a tough choice for us to help you on. Usualy you want to go with the more reliable of the two. That varies from area to area. I know around here DSL is better, but go across the country and Cable rocks. What you really need to do is talk with people who use both services and ask there opinion. Call tech support and find out things like mean time to repair (If i have a problem, how long to fix), what rates are guaranteed, do they allow servers? what's expected of you. Sign up fees. Do you need to buy your equipment or can you rent.
Some companies will provide great service in one area of town, but accross the street (litteraly) the service is very crappy.

Now for the two companies you've mentioned.. I've heard both good and bad from both of ehm.

If both compaies allow equipment rental, go with one, try it out, if you hate it, switch. I would avoid purchasing your modem until your satisfied on the quality of service.