I would personally recommend the equivalent of [email protected], which is the format I use. I agree with your assessment — to me, emails like [email protected] and [email protected] seem a bit too playful or informal. I like to use one email address across all the services I use, so something that is completely neutral is key. Hard to get more neutral than [email protected], in my opinion.

The benefit to [email protected] is that it helps reinforce the fact that this person is, indeed, emailing you, and no one else. [email protected] would probably work in most contexts, but to me it adds a layer of ambiguity — when I see that, I have to think twice and make sure that there's no one else who would be receiving this email ("is this really going to John, or is there a dedicated support person answering emails?"). This is less problematic when it's someone's personal site, but for small businesses where it's really not clear whether there might be a support staff responding to emails, I then have to look it up and potentially resort to omitting a name in the salutation of my email, or writing "Dear John Doe Support", or something similar. Not optimal.

Lastly, I live in America but have a non-American first name, which gets misspelled a lot. Having to type my first name twice in my email address helps reinforce the spelling, leading to less awkwardness for the other person.