I prefer to watch in a group but I end up having to watch it again on my own because all the chatter causes me to miss things.
One of my favourite times was with a couple of mates watching summerslam. We got wrecked and talked about WCW through the whole thing and only caught the bit where Undertaker sent Edge all the way to hell.
Alone, mostly. Sometimes I watch some stuff with my Dad, it's fun. And I have watched only one time with friends (It was the ME of WM31), it was annoying since one of my friends didn't shut up. So, mostly, I watch alone or with my dad.
There is nothing like enjoying a WWE PPV with some good mates, good food, and several cold beers. However I generally do watch the event or my favorite matches again later on to catch some of the more subtle nuances.