My area has both DBSA and NAMI meetings. They are the most formal meetings and have trained facilitators, mostly peer led. If you go to their websites you can find location look ups. Both organizations have many locations throughout the US. I know from a Canadian friend that Canada has similar groups, but under different names. I could always ask her for more details if there is an interested Canadian.

I suppose local libraries and hospitals could be places for mental health support groups. If they don't have one, you could always ask if they could set one up, at least temporarily. They can market/advertise such groups along with other ones they have.

Though much more casual, there are Meet Up groups for all sorts of things. If there isn't one in your area, you can create one yourself. Some are listed at All Bipolar Disorder Meetups - Meetup

I have really only been to DBSA meetings. I didn't find them competitive at all, but can't speak for others. Occasionally there was an annoying person I had to tolerate. Occasionally when my mood was elevated, people probably had to tolerate me. The facilitators are trained to recognize this and do their best to make the meetings as comfortable as possible.