There's loads of variations these days. 5/6/7 a side, 11 a side, Futsall, Street football or just a general kick about with your mates/family.
I've always loved 6/7 a side but it's always tough to find anywhere that does it.
Playing 5 a side at the moment and loving it. I think I'm enjoying it more now as one of our players has moved on as my god did he moan. It's amazing how one negative aspect being removed can increase enjoyment levels.
Although I did enjoy 11 a side it was always crap if you're a sub for 80 minutes. If you paid me to do it I'd be fine with it, but paying for the privilege is another matter.