I'm fairly picky about eye masks, but mostly the need for contouring so they don't push on my lids.

I like this MZOO one purchased on Amazon right now:

The MZOO has an adjustable strap.

My child uses it, and this was a kid with a giant noggin growing up. I haven't measured his cranium lately, but his dad has a big head, too, so I think this could indicate a longer than average strap.