People will argue against cable because it's shared. So is DSL. You're sharing the ISP's maximum bandwidth. If they have a T3 for every 100 customers, you're not always going to get your full bandwidth (that was just an example).
People will argue against cable because it's broadcast based, and easier to "hack". Secure your system (firewall, unbind File and Print Sharing from TCP/IP or disable it alltogether) and you're fine.
People will argue against DSL because "cable is faster". It all depends on where you live. The $40 service level here in Vegas will get you 512/128 from cable and from Sprint/Earthlink DSL. $100 a month will get you 1.0/256 cable or 1.5/384 DSL.
People will argue against DSL because it's not as reliable (I've seen it). Here in Vegas, the cable company gives me 60% packetloss to the DNS servers, no less to anything else. DSL gives me an average ping of 80-120 with very, very little packet loss. Again, all depends on the area.
I've had my cable modem for over 4 years now. I've had DSL for about 4-6 months. In Vegas, cable blows. The only advantage it had here was lower install costs, but now that the DSL modem is being bundled with the service, there's no competition. And as soon as my contract is up with Earthlink, I'm going with Speakeasy DSL and running a server. That's the BIGGEST advantage to DSL. You get to pick your provider.