Ability to sort and search personal stats.
The Top 20s have been a really fun aspect of the site for me--watching characters arrive or be pushed out as I go through deep dives into their appearances is a delight. The problem, of course, is how clunky that data is, as well as how inaccessible.
I've been bothered by the cluttering of Personas in personal reading stats; it seems like it would be great to see all your personal stats of (for example) Jean Grey without her having separate entries under her four other personas.
There are characters I've been reading a lot of who would most certainly be in my top 20--or would be in a radically different place in that list--if it were accounting for all appearances of the baseline character.
Further, having a streamlined 'search' function for those Top 20 lists could be an exciting tool so that you could look up where a character ranks for you.
With sorting options, one could even sort in reverse order to see which characters are the most neglected in their collecting and reading.