Argh, I can't decide. This is like sticking two types of chocolate together and making me choose which one I prefer....
Personally, Star Wars is epic. I will always love Jedi, even if I prefer Knights of the Old Republic to the movie verse, but whatev. Revan will always be my favorite, followed closely by the Exile. But, Hans Solo was awesome and had the best actor ever.
As for the Avengers, I will always fangirl over Captain America, Thor, and Hawkeye. Love them. Of course the rest of the team is great too. Ironman is an icon, but Cap will always be my fav. And of course Loki is a great trickster, since he's not exactly a villain...he is in the movie obviously but, most of the time Loki's motivated by his own pleasure/fun.
To sum up...I think I'm gonna have to go with the Avengers, just because this day will 'always' belong to Star Wars but, I've been looking forward to the new movie for MONTHS.