So, I've checked the numbers, and as you said Iruka and Kakashi are still very popular. The Naruto fandom has 3762 complete English-language 1000+ words fics. Kakashi throws 1232 fics with the same parameters, Iruka 603.

Teen Wolf has 23173 fics after filtering, which means a character needs less than 1159 fics to be eligible. Melissa McCall, unfortunately, has 1754. The rest is all good.