I've had both.
Cable:
When I first got my cable modem, it was very unstable. At least 3 or 4 times a week, the connection would go down for hours at a time. This happened for a good 4 months. However, they must have fixed or upgraded something, because after that the connection was solid.
Generally speaking, with cable modem you're sharing the network with everyone else in your neighborhood who has a cable modem. If you try to surf the Web during peak hours, the connection will probably be much slower than you're used to. I never had the speeds become prohibitively slow, and during the off-peak hours, everything moved like greased lightning.
If you're a techo-geek and you like to run different servers, be aware that many cable Internet providers block common ports, making it more difficult to do things like run a Web server, email server, etc. Of course the crappy upload speeds don't help much, either.
DSL:
I have had DSL for about 4 months now and it rocks. I have never experienced a slowdown, and the connection has only been down once. The upload speed is still pretty terrible, but that doesn't matter unless you're serving files up on the Internet or consistently sending LARGE emails.
My vote: DSL
But if DSL were to suddenly became unavailble, I wouldn't hesitate to go back to cable.
Here are some links that might help:
http://www.google.com/search?hl=en&l...s.+cable+modem
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