Joplin has multiple sync options. Other than Nextcloud, you can use OneDrive, Dropbox, and they have a subscription service as well.
Obsidian is another to look at, but you need to either pay for sync or bring your own sync (~~though I don't know that you can sync to mobile without using their sync~~ edit: see below comment by @fossisfun@lemmy.ml that explains how to do it).
I think it's probably helpful to know if sync across platforms is important to you, and if so, whether you're willing to pay for it. I'm not sure that there are really many alternatives to an app provided for free with free syncing - that costs money to provide and honestly I'd be a bit dubious about using a service like that.