I bet for the things you’ve used it for it’s been great!
I’m pretty sure that people have made that comparison and that 100-1000X as many images are running on Docker than on LXC (which I did use, once upon a time).
I’m not saying that Proxmox is bad, but if you want Discourse to be easy to set up and maintain, you’ll use Docker. For a frame of reference, if you were to ask for help on Marketplace with a budget of under $1,000 I wouldn’t respond.