I upgraded both my Dish and GCI equipment a couple of weeks ago and thought that I would offer my opinion on the Dish 622 vs GCI TDC775 Tahoe.
All channels except locals: Dish. The picture has better detail and less motion artifacts.
Locals: GCI. Dish does not carry the local channels in HD. I do have a rooftop antenna connected, but Dish does not have the EPG info for KAKM HD and the guide for KTVA HD shows the info for NBC.
This makes it very hard to set the DVR to record any HD off of either 7 or 11. The 622 Channel 2 HD does show the correct info. The 622 OTA for 2, 7 and 11 picture quality is better than GCI. However, the problems with the EPG out weigh the slight difference in picture quality.
User interface: Dish. I can record 3 channels simultaneously (2 from satellite and one OTA), the PIP works, the hard drive is bigger for about 200 hours of SD storage, the channels are in a better order in the guide, the guide is faster to scroll thru, no TV guide ads in the guide, 4 favorite lists instead of 1, Dish has Name Based Recording (record only new episodes of a program skipping repeats for example) and a 30 second skip forward.
Costs: comparable, but Dish just raised the price $5/month for the "everything" package. and I have not sat down with the bills to do a complete comparison.
Number of channels available: Comparable. Each has a few minor channels that the other does not. GCI has Starz HD, Dish does not. Dish has the old Voom channels on satellite 129, but due to problems with it, Alaska can not get it. Perhaps they will fix it in the future with the launch of a new satellite.
Bottom line for me: Dish. Just my 2 cents worth.