Which is better, Cable Modem or DSL ?
There is no simple answer to the question, it depends on your area, ISP, Internet congestion at the time, time of day, moon phase(JK) and your needs. One of the major advantages of DSL over Cable Modems is that the line is not shared to the Central Office, however, the slow connections are rarely associated with this segment of your connection. Cable Modems have higher bandwidth, however the connection is shared and as a result the performance is similar to DSL.
Generally, Cable Modems can achieve better throughput, which varies a lot, while DSL usually provides a more constant feed, with lower latency.
A common misconception is that DSL is dedicated bandwidth, while Cable modems provide shared medium. This is only true for the segment between you and the ISP's central office, and that is rarely the bottleneck of the connection. From the Central Office out to the Internet, both Cable and DSL share your ISP's backbones, whatever they are. Residential broadband is oversubscribed, whether cable or DSL - usually with 10 times as many subscribers as the maximum backbone capacity. Since the backbones are most likely the bottleneck of the connection, and it is shared medium, both residential DSL and Cable may experience slowdowns at peak times.