Joplin is pretty good I think it has nice markdown features and it has a sick theme which I really like. However the downside is that it doesn't really have its own inbuilt syncing like Standard notes does. Yes I get it you can use Dropbox, however Dropbox has privacy issues and for Android since afaik Dropbox doesn't store files on the device, I don't think this is the best idea.
Additionally just like with Standard notes, I wish it would support device encryption for Windows, Mac, Android and Linux.
The thing is, the answer to all your questions can be found in the forum, so why not start there? For encryption, the post just right next to yours is all about this. Mega has been discussed countless time too, and for E2EE you've been given a link that explains it.