It really depends on which part of the country you are in. Cable here is really bad. DSL is much better. Of course, it depends on the flavor of DSL you have available in your area too. DSL encompasses a very wide range of product.
Overall, DSL should be better as you are not sharing the physical connection with everyone in your neighborhood. That alone makes it more secure and potentially more stable.
Best thing to do is to find people locally and ask them what they have experienced.