Church, hands down. However, I would get involved in lots of stuff, stay after for coffee hour, and I also have absolutely no issues at all striking up conversations with people, even if I'm the new one.
at newer people at my church who after months complain they don't know anyone, don't have any friends in the congregation, etc. But upon asking a few questions, I find out they rarely stay for coffee hour, don't get involved in ANYTHING, won't even go up to people and introduce themselves.
You just can't show up, you have to make some effort.
I also like having friends in a wide range of ages. I have single friends my age (early 40s), but then I also have married friends (with kids) who are 10-15 years younger than I, as well as very good friends 10-15 years older. One lady I love dearly is 77!