It greatly depends on the provider, but overall unless you've got a ****ty cable provider, Cable's going to beat the pants off of DSL.
AT&T Broadband has *GREAT* ping times due to it's routing (I see around 50-100 ms on half-life games, and 10-75 or so on UT/INF games. Halflife local bots ping at 15, so.)
Download speeds, Cable spanks DSL for download speeds unless you live in canada, where they offer some of the 1.5mbit DSL for reasonable prices (here in colorado, anything over 256k costs you $$$), I generally see 1.5 mb/sec downloads, but I've seen as high as 10 mbit. (seriously).
Upload speeds, both are going to be about the same, ATTBI is capped at about 128k up, so are the local DSL lines. Generally you have to pay $$$ for more than 128k up. I think Qwest charges an assload for you to get 256, and above that it's just insane.
Reliability, well, I live in Qwest (USwest) territory - DSL lines simply don't stay up in most neighborhoods that have them.
Excuses range from "Well you are pretty far from the co" (guy was a whole 100 yards from it) to "Sunlight is interfering with the fiber lines" - both are serious responses from Qwest technical support.
Your local DSL provider will probobly be better than qwest.
As for cable, the only downtime I've had was when a truck slammed into the node a couple years ago, (wound up being a qwest truck too, heh!) and then again when @home went kerplewie, but I was up a couple days later, and it's been alot better directly under AT&T - lets face it, Ma Bell knows how to get **** done.
Prices, Cable's cheaper than DSL in my area, but, YOUR RESULTS MAY VARY.