It might too late, but you should be aware that all Comcast channels other than local broadcast stations are sent via 720p/60. When they did their conversion from MPEG2 to MPEG4 they also down-rezzed all the 1080i channels to 720p.
60fps is great and 720p vs 1080i are similar enough that I couldn't care less.
I ran them side by side the last 2 weeks and at least here the quality differences are negligible but there are differences.
They do have fewer pay stations in HD that Directv. If I subbed those I'd care more but I don't.
Few stations like Nickjr and Disney JR are not in HD. Kids don't mind, neither do I but that is different.
Everything that I watch is in HD and what most people would watch. The quality on most of those are pretty tit for tat with D*. Close enough that most people probably wouldn't care if any difference. Sd is obviously much improved compared to D* but who cares about that?
X1 vs Genie is also pretty tit for tat.
They both have issues with a hang up or graphics glitches from time to time. I think the x1 is more consistent speed wise but not perfect.
They feel pretty similar in function. Start program over when you select it late from the guide, record options are similar etc. They don't have multiple listings in the x1 for long recordings like D* which is nice.
I think the x1 has a better search for sure and xfinity has much better on demand options in addition to the phone app which is superior. D* has slightly faster animations on the genie which is a slight advantage and one less button press for my shows which was nice. X1 has better skipping options and the fast forward works better for me, faster as well. I like 15second and 30 second skip back options in addition to the regular 30 second skip. X1 has a better guide (more hours) and better look / presentation of information. The advertisements in the guide are also far fewer and much less obnoxious.
Really though they are pretty even DVR wise for the most part. There are differences but honestly either should work well for just about anyone.
The xfinity app is really nice and I have full access to my dvr while away and all my shows. Very high speed. Works much better and smoother than the directv app. Also zero rated so kids can use the app and Rokus etc without worry.
On demand there is no comparison. D* on demand sucks comparatively.
Price, also no comparison. We'll see how that goes in the future but I'll gladly drop xfinity for Vue or Sling or Hulu etc. Plenty of options. I think the days of paying $145-160 a month for just TV (no pay stations) are quickly coming to a close and D* better enjoy it while it lasts because competition is starting to ramp up. If they ever lose Sunday ticket they'll really be screwed.