Anything over 20 megs on cable is a waste, since I doubt most people can top 10 during the evening hours. I have 20 now, but get only 5-6 at night. The upgrade from 10 to 20 is only a few bucks, so I don't feel like I'm getting ripped off.
Which cable provider are you using? Suddenlink? If not then it isn't a valid comparison; where Suddenlink has launched DOCSIS 3 they're pretty good about keeping the network running at top speed.