asking your neighbours would be the best option
adsl and cable are different technologies.
cable is faster in connecting your house to the isp. sometimes as few as 3ms. this is because no conversion is needed (its ethernet to ethernet)
In adsl the signal has to be converted to ethernet until it reaches the isp (i believe its called modulation, i can't say for sure). This results in few ms extra (5-15ms).
In adsl the distance between your home and the nearest central is crucial. <1km is best.
in cable, the number of ppl connected in your area (cell) is the most important. Watchout for "high times" - usually between 18h and 24h (at least in Portugal). between these hours the cell may get more traffic it can handle and the ping may be higher.
Which one is the best?
Depends on your location (and the isp itself*). Hence "ask the neighbours". Both are good. both have flaws. just make the right choice
* Of course, the isp routing is important also. choose an isp that's good for games (low latency to qw servers