Well, I haven't played 5-a-side/7-a-side football, whatever other forms of football there are. I've only played 11-a-side.
I have played 15-a-side rugby, and 7-a-side, and all I can say is that the orthodox form of any sport is much better. It's constructed to be tougher than modifications (which are made for obvious reasons, make it easier to play/understand). Also, tries are, what's the word, more "precious" in 15-a-side/orthodox rugby union than in 7-a-side, where tries come and go like a slutty chick.
Guess it's the same for 11-a-side footy, tougher conditions -> work harder to produce goals.