TBH, I've never had a major problem with Comcast Xfinity.. I live in Ft. Lauderdale so maybe it's different down here? Their internet is super consistent (I pay for 75mb down and constantly receive about 110mb down) and the X1 tv system is pretty cool (although I like DirecTV's OS better but they're so expensive).
The ONLY think I dislike about comcast are the few times in the last couple years I try to trouble shoot my modem, they start off assuming I know nothing about tech. Yes, that's probably a good thing for most people but they should have a different number to call if you've done all the common sense stuff first, and if you have more advanced knowledge to work through troubleshooting faster.