I am primarily a solitary gamer but I have played and enjoyed many games from every genre. Whenever I do play online games I play co-op, although I did go through a long phase of competitive WC3/SC with my friends in the past. I think there are a lot of gamers like this out there, probably more than there are gamers who like competitive online.
The reason that Uncharted 2 isn't my GOTY is because it isn't much fun to replay the campaign, especially soon after beating it the first time. Finding the treasures was a chore and offered no immediate benefits, and they don't feel like they fit with the pacing of the game. The survival and gold rush modes are fun but I can easily stop playing them like I did Horde and Firefight and never look back. I only beat it a second time because I wanted the Platinum (I got it for Uncharted 1 as well so I wanted them both as a set).
With Borderlands, the campaign is longer, the "one more mission" mmo-style structure is addicting even if it is narratively weak, and I actually want to play the game again for fun, not just for the trophies (but I am going for all the trophies). In Borderlands, it is the gameplay mechanics of the shooting/looting/questing that keep me hooked, not the story telling, so when I've seen the story unfold that won't affect my enjoyment of the game when I replay it.
That said, Borderlands has very clear faults. The skill trees aren't deep enough to result in wildly varied builds by the time you are level 50 (Diablo 2 had a dozen viable builds per character if you didn't need to be able to unlock and solo the Ubers or play Hardcore mode). There appear to be at most 2 viable builds per class, since at level 50 you can make 2 of your 3 skill trees useful by the time you hit the level cap (assuming your mostly passive tree is the one that overlaps). There is no trade screen, so trading goes by honor system and you can't view each other's stuff safely. There isn't enough end-game content. If there were 1-2 optional dungeons that were long and hard, with an uber boss at the end that had 1/1000 chance of dropping one of several super unique items with unique appearance, the game would be much better. Hopefully Borderlands 2 fixes everything. The DLC won't be able to deepen the skill trees or add more visual polish (cmon, water that doesn't splash when you drive through it?) but it could potentially address the lack of end-game content.
Uncharted 2 is a great game, possibly the best game of it's highly scripted and cinematically narrated type. However, it's certainly not going to be as good to every type of gamer. I rate games based on how much fun I have and how much I want to keep playing them. Uncharted 2 is possibly as good as a game can be without RPG/NG+ elements. However, I prefer games with RPG/NG+ elements, so Borderlands might be my GOTY depending on how I feel about Demon's Souls when I get around to unwrapping it.