I sometimes do a long post on the differences in sat systems but I'll keep it short here
Dish advertises "The lowest price" and they do have the most channels, but.. They seem to be related to KOA (Keep On Adding) and often that lowest price, by the time they are done, is higher than Direc, and who needs 1,000+ Channels?
Second, do not get a house account and use the spare receiver in your RV.. Do it the other way around. (Get an RV account and use the spare receiver in your house)
Now. there are 4 grades of service in the US not counting "Free to Air" which really is not that great a deal for Rvers (You won't get NBC, CBS, and so on)
DirecTV (Normal, not high def) Easiest antenna to point, however aiming software not that great
DISH (normal) Best pointing software out there, but you need to hit 2 birds, which means you have one more setting and lots of folks have issues understanding how to aim.> It really is easy.
Dish HDTV Two different antennas depending on where you are parked, 3 birds each. Truly no harder to aim
DirecHDTV.. Special antenna, 2 bands, very critical on pointing but once you get used to it should not be an issue
Network TV (ABC, CBS and so on) if you are close to home you get local stations, but with very few exceptions if you are "Out and about" you won't be able to get 'em.. You need DISTANT NETWORK SERVICE, which of course, costs money,, Direc offeres that on your regular bill, With Dish you contract with a 3rd party provider, prices about the same for both.. NOTE: THIS is the reason I said "Get an RV account"
Getting an RV account may take 10 or 20 calls to Direc, the idiot clerks do not understand and keep transfering you to KVH.. Tell 'em if they do that you are calling DISH and perhaps you can avoid making as many calls as I had to make.
Finally the install.. Now, folks tell you to use the park-cable for sat, and tell you how to do it
Forget that. Run a nice new RG-6, (and quality cable) to a basement or bulkhead connector, And forget the existing cable. If you have one TV in the trailer hook up is as per the Sat-Receiver manual If you have more.. Ask and I'll tell you how to do it and keep the option of using park cable.