A popular guild in my area has 400+ members and is very structured. Newest members somehow get "elected" as officers. How fun can that be? The only advantage I see is members get a percentage off purchases at local shops.
My preference is a small group where you can interact with each other. I don't belong to a guild.
A small shop close by encourages quilters to just come by and sit-n-sew. One day I'll try that out to see if it works for me.