The good thing about Marvel's sales is that if you don't like it, wait a few days. They have sales twice a week. I just picked up a ton of Captain America issues on Monday, a bunch of Ultron stories on Tuesday, and the Jason Aaron Hulks today.
DC's sales only come every few weeks. The last DC sale comic I got was in June. The last few DC sales have been useless to me.
If last year is any indication, the holiday sales next month should be amazing. I bought most of Jason Aaron's Wolverine and all of Gotham Central last year.
I like the frequency of Marvel's sales - and did pretty well with Cap and the Annihilation Conquest sale, but for the most part they put something I don't like on sale two or three times a week. It may be my tastes, but the stuff I really want to get almost never goes on sale, and I hate seeing stuff I hate on sale all the time. Also, their sales are so small, that each one only appeals to a narrow band of tastes. I'd say at least 90% of Marvel's sales are for books I have no interest in.
DC's sales are rarer, which I don't like, but often wider - making it easier for me to find something I like on sale even if there's a lot I don't care for.