I've been agonising over this too.
There are many options, but all have negatives: restricted platforms, relatively expensive subscriptions, no hidden markdown, or just plain ugly.
My favourite would be Typora if there was an iOS app; but it's just Windows or MacOS. For me that's a big but.
Next is the beautiful Bear Notes, but it's Apple ecosystem only, and displays distracting heading markdown.
Dropbox Paper is great, but although it has excellent mobile apps, it has no off-line access on the Desktop. It's handling of images and other attachments in notes is outstanding. I