If you’re lucky enough to have both DSL and cable available, you can choose the one you get for speed and price reasons.
Outside of that, just remember that DSL is a dedicated line to you only. The speed and capacity will not vary if your neighbors get online and start playing games, because they have their own, dedicated lines, too.
Cable is a shared medium, and if your neighborhood is overloaded with users, your speed and capacity will be adversely affected. The cable company can avoid this by adding more fiber, but they might not be as quick to expand as you might like.
As far as how likely this is to happen IRL, I cannot give you any experience, as I only have cable in my neighborhood at 5Mb/sec download (3 and 10 is available) and I love it.
Satellite is available anywhere, but tends to be more expensive both for installation and monthly charges. Beyond that, it offers great speed, but suffers from latency (delays in roundtrip signals) since the signal has to travel a long ways and the distance is a noticable fraction of the speed of light. This bothers gamers, who need a fast connection in both directions, but might not bother a typical Internet browser person. So satellite is the last-ditch choice for remote locations where the alternative is only dialup.
When you compare speeds, always check the rate both down and up. They are often not the same; down is faster than up by a factor of 10. Then consider your expected use. A typical online user is browsing web pages; he sends a small packet of requests and is rewarded with a large flood of data. This suits the asymmetric process well, but YMMV.
Another consideration. Many cable companies now provide phone lines, and cheaper than Ma Bell. If you subscribe to both phone and Internet, you may get a discount for bundling. I dropped AT&T after using them all my life and now I get Internet, TV and phone thru the cable provider.