As mentioned earlier, the typical problems of Author Avatars
- becoming mouthpieces for the author, too much favoritism even if they aren't
an outright Mary Sue
, et cetera.
These are not inherent or unavoidable problems, but even the risk of them can be avoided completely by simply not basing a character off yourself in the first place. And while there are certainly benefits to letting some aspects of your personality into your characters
, I can't see any real benefit that would come from basing a single
character off of yourself. So I say it's just best to avoid the whole thing to begin with.