Jack Donaghy from 30 Rock
I bet you thought I was going to say Tracy Jordan, but guess what? Tracy Jordan would be right up there with Liz Lemon as the worst party guest because he'd probably end up bringing a tiger to your house that would maul half the guests. Jack Donaghy, on the other hand, would be the perfect party guest. He can hold his liquor, he looks good in a suit, and he'd definitely bring a bottle of fancy champagne since he has money coming out his ears. It's a win/win.
Shoshanna Shapiro from Girls
All of the Girls characters are kind of insufferable, aren't they? Shoshanna is pretty fun, as far as neurotic main characters go. She accidentally smoked crack at a party! The hilarity! Since she never shuts up, at least that'd be an entertaining story for everyone who walks within earshot.
Schmidt from New Girl
Schmidt is a delightful douchebag. He knows all the cool party spots, and he's willing to spend money he doesn't have to make sure everyone has a good time. While you may have to tell him to put a dollar in the douchebag jar, Schmidt will have everyone partying in fancy Italian loafers until the sun comes up.
Linda from Bob's Burgers
LINDAAAA! That voice. Linda would be the light of any holiday party. She's always singing terrible songs about whatever is going on around her, and you can't help but love her.
Andy Dwyer from Parks and Recreation
Duh, because Andy is the best.