Personaly, I play the MFCA ruleset, and I added a bit of buzzball rules too (passing simulation).
I also added my own rules, for "realistic" action :
front of base tackling
offense pivots forbidden for pass simulation (the receiver can't pivot)
timing restrictions (you have to choose the receiver instantly, for example)
the goal is to make the game fast and easy to play (remember that I'm playing with beginners here), but keeping some real football aspects in the game.
Definitly not a hardcore football simulation, but looks football enough for us
