Proxmox definitely has a harder set-up i am currently doing it right now and I've found it a bit of a learning curve, but it is definitely the ultimately better and more fun option if you ask me ;)
Someone should correct me if I'm wrong but auto update should be as easy as scheduling the commands for apt or whatever package manager your using to update.
I haven't used nextcloud but it seems frustrating that there isn't any really good selfhosted file cloud. Nextcloud is really chunky and inefficient but it seems to be the best option despite that.