Sorry! I meant for my post to be in response to the original, so:
I like it a lot!
I think it came to mind for me of a name I'd seriously consider because of alliteration with my last name:
Marcus Mustard. However, it reminds me of
Marcus Mumford (of Mumford and Sons) which kinda discourages me from using it. But I think it's fun to say and easy to spell. I like the spelling
Markus too, visually. Though that may get misspelled more often (even my spell check doesn't recognize
Markus). Still, I think the name is different without being too weird in the US.
For associations, I once had a student with this name who was the sweetest kid, so it has a positive association. Though, ironically, my biggest childhood bully was named
Marcus, but that doesn't deter me from using it since it was so long ago. Also,
Marcus Aurelius has a general positive association too with his Meditations.
Anyway, I'd say, it's a solid choice! Probably in my top 5 the more I think about it.