DSL is good if you want to host servers of any kind...FTP, gaming, web, etc.
Mainly because cable will disconnect and reconnect constantly.
Cable is faster, but your upload speed can be really bad. I have a friend who gets like 3000k/128k. I get 640k/272k. Most DSL services give you at least 256k upload.
If you just want an upgrade from your dialup that goes faster, but you're not looking for something really robust, go with cable.
If you want to get into more complex networking and possibly host a few servers, go with DSL.
You really do get what you pay for. Its an issue of Quality vs Quantity. For what I do, cable would be better...but my roommate hosts servers so he needs DSL. So I really don't mind.