@Villan You say that Villa are above the big club argument, yet the other Villa fan is coming on here sounding very argumentative and aggressive to prove that Villa are a bigger club. You've been pretty reasonable about it from reading a couple of posts but there is no need to come on another teams forum and start ridiculing them like he has. Just don't understand it personally.
As a neutral in the debate, I would have to say that I view Villa as the bigger club. Both are great traditional clubs and as has been mentioned, both have certain things that make them up there with the biggest clubs. Sunderland's current crowds are much better and loyal than Villa's, and it's certainly an important factor. Where I would disagree with some on here though is that it is not the only factor. And whilst both clubs are under performing on the pitch currently, if you look over history, then Villa have had far more impressive achievements. They've won a European Cup, but as opposed to Forest, they have several other things that make them huge that Forest don't have. Years in the top flight, record attendance, European Cup, League Titles and other domestic success. I think where Villa fall down in comparison even to us is that most of their success was pre War. 1 league title in over 100 years is abysmal and their success isn't as impressive as they claim it to be given that they've won so little after that pre 1900 success.
I think if you're also looking in the Premier League era to keep things more recent, Sunderland's performances on the pitch have been mostly terrible whereas Villa have at least competed for a few seasons. They were a decent team under O'Neill and played in Europe for a bit, and in the 90's they had quite a few top 6 finishes. That's what fans of other clubs will remember when having this debate. Crowds alone don't make a club bigger, which is why I mentioned Hertha Berlin in Germany who average about 50,000 yet aren't a big club.
As others have said, the big club debate is all a bit pathetic when fans of Everton, Newcastle, Sunderland and Villa are arguing about it to put eachother down. It's great to have a history to be proud of, but all of us are failing to compete at the top whilst City and Chelsea dominate. The fact we've all had success years ago continues to be forgotten and soon huge clubs like Liverpool will join us in only being able to talk about the past. 25 years without a title for them and I don't see it changing any time soon.
The good thing about each of our clubs is that we support them because they're our team. We don't need to win trophies to carry on supporting them like a large % of Chelsea, City and Man United do.