I like stuff from both of them, but I tend to feel like NBC pushes more winter stuff that I don't care about. There's stuff I don't care about in the summer olympics, too, but I don't feel like it's pushed at me as much.
There's quite a few more medals up for grabs and sports in play for the summer, too, and I like having a wider variety to choose from. I like spending the extra time on it, which is more a matter of personal taste.
Last thing- in recent memory, it seems like the summer olympics have been a bigger deal for the host country. China had an enormous coming out party, it's not as big a deal for England by comparison but it seems like it'll do more for their international sports than Turin/Torino did for Italy or Salt Lake did for the US, and then Rio is approaching on the horizon and I'm thinking that will rival China as far as how big a deal it is for the country on the world stage. Again, this is just in recent memory, and it may have more to do with the fact that northern-hemisphere countries tend to be better at winter sports while also having less to gain from the Games. And then the countries further south as well as in the southern hemisphere tend to have more to offer in the summer games while also having more to gain from them on the whole. This might just be a little bit of recent memory playing a role, but I also think there's something to the idea that the summer games tend to do more for the host country than winter games tend to do for a host country. All of that means at least as much to me as any one of the sports or athletes themselves, so it has a pretty significant sort-of-background effect on what I'm thinking in a given Olympic year.