Why so much misinformation?
DSL isn't a "private" connection as it is marketed. The "dedicated line" idea is only from your home/business to the DSLAM. After that, you are sharing bandwidth with everyone else. Think about it. Do you think they are running a direct line from your house to a router for you alone?
As for "which is better", the answer is either/neither/or. You've got to ask around to people using the various services in your market. In some areas, DSL is superior in performance, but in other areas, Cable offers superior performance for less money. In some areas, neither is a good choice (because of high cost and/or poor network performance on either.) No technology is "best" 100% of the time for every particular situation.
Overall, DSL offers better ping times but less overall performance and at a significantly higher cost than Cable.