From personal experience Cable beats DSL in everyway, except price if you are willing to accept slower speeds. That said it has been several years since I last used DSL. But I found that Cable is faster, more stable/reliable, and has always been available in the areas I needed broadband service. I also found better customer service when problems occurred from our cable broadband provider than the phone company.
That's just my opinion.
Though this CNet review/comparison agrees with some of my arguments.
(not sure when it was published).
http://reviews.cnet.com/452..
.It looks like DSL is still quicker to get setup in most cases since every building has a phone jack, while a line might need run to get Cable at your business location.
Cable seems to have the majority market share. But again it tends to be more pricey, sometimes disproportionately so in relation to the speed advantages.
But in terms of speed, I believe ADSL and SDSL caps out under 10Mbps while Cable can reach 30Mbps. Though if you can get VDSL in your area I understand that it is comparable.
Theoretically Cable can slow down if too many people are using it at the same time, though in practice I have rarely witnessed this "clogging" of the pipe.
I hope this helps. Good luck.