It depends, really. In my experience, cable can be faster than DSL (the vast majority of DSL is capped at 1.5Mbps, tops), but in practice, during heavy net traffic in your "cable neighborhood," cable can be slower.
Let me put it this way- My cable(Road Runner) runs as fast as 4Mbps download, depending on time of day. It has been as slow as 400Kbps on Sunday evenings (seems to be the heaviest time). My friend's DSL (Bellsouth) typically is consistent (and tops) at 1Mbps, but on Sunday evenings, down to 500Kbps, or so.
Ping times are typically much higher on cable. If you play online real-time games, this needs to be low. DSL rules this.
People say DSL gets you a dedicated pipe, but that's not really true. It just moves the bottleneck further up the pipe, to the switching office's routers, as opposed to the one in your "cable neighborhood."
If online gaming isn't your thing, go with the lowest price.
I've had both. Overall, my cable modem delivered greater speed. It's true that the "sharing" problem occurs at times, but at night (are you a night owl, too?) I got optimum speed, much faster than the DSL.
Keep in mind that I tweaked the MTU's, etc. and also shut down the software proxy that was a bottleneck.
Norm, I would go with cable. I know in my area DSL is capped at about 600 Kbps on downloads and 128 kbps on uploads. If you want 1.5 kbps DSL you have to pay even more of a premium over the standard DSL service which cost more then 1.5 Mbps cable already.
I wish both services would allow faster upload speeds, but the are trying to keep people from running web servers. For me cable was faster, cheaper, and right now I am one of the few people with the service in my town, so I get no slow downs. Your are may be a bit different though.
I think in most cases cable will give you better download speeds. However, it has been my experience that DSL seems to perform better in response time (pings). Of course this will probably vary somewhat depending on your particular area and the service providers involved. If you are a gamer and want the best online performance I would lean towards DSL, otherwise cable.
About Ping times and cable, this is not always true. Its the network infrastructure that has the most play on this. With me being in Oklahoma I have a lot of choices for game servers all over the country. With Jedi Knight Outcast I always see many many serviers with 50ms and below pings.