Some quick thoughts...

Finding an address of all CAPS or all lowercase, is fairly simple these days. Not sure if they are needed on a leader board. However, all digits/numbers is worthy. It is fairly easy to tie the OG record, 18 leading digits, but above that could be challenging.
Finding a palindrome address, to match the OG record of 4/8 is pretty easy. I can find 100s to 1000s of these in a day. But 5/10+ could be challenging.
Shortest address will be interesting to see if anyone can beat the OG record of 31 characters.

The other ones, longest real-word prefix and pronounceable will be interesting lol.