I'll have to agree with Mike. DTV has more, but DISH has better variety.
DISH also seems to have better customer service from what I've heard.
Believe it or not, it was the UPN content that won me over with DISH. I had moved from an area that had UPN to one that didn't - and I had to get Voyager, after all. ;-}
Then when the local cable system dropped Comedy Central, that sealed it.

All in all, I've really enjoyed DISH.