I like
Baltazar. It reminds me of
Sebastian Baltazar Bucks on the Neverending Story movie series. He was a child, so I guess the image of an old wise man is second to my image of the kid. I think it is a nice combo. I also believe there is a difference in the pronunciations of the names you listed. The first two I have heard pronounced Bal-tuh-czar whereas the last two I have heard Bal-thu-czar. I like both pronunciations. I also like all of the spellings, but I am not as keen on
Baltasar simply because it looks like something is missing. I think if I was to know someone named
Baltazar I would nn him something like Czar or Balty.
I hope that helps.