For osu! mania, I believe it would be beneficial to add a new search option category based on key count (to the official Osu! website).
For many Osu! mania players, there's an obvious key count preference. It is commonly known that 7k and 4k are the most common, but there isn't a way for players to specifically categorize these key counts on the official Osu! website. Adding this feature means a much clearer accessibility to each players preference.
What about searching for your preference in the search bar?
As you may have noticed, searching 7k does bring up mostly 7k songs, however it is notable that there's no organization to the songs when their brought up in a search. Adding said feature would (hopefully) make it possible to categorize songs chronologically, while also staying true to the users key count preference.
What would this look like?
Under "More Search Options" on the official Osu! website, there would be the option to categorize songs based on key count, ranging from 1-10 (and possibly reminding players that some key counts are not ranked) or 4-10. It might look something like this:
Why I personally would like to see the key count search option
I've actually had this idea for some time, in fact I noted the thought back when I first started playing Osu! mania. I'm aware that many others have had similar thoughts, but like me, probably brushed them off because of my previous statement (it is possible to search 7k in the search bar). I'm mentioning it now only because I'm hoping to get better on 7k, and think it's an Idea worth considering. I also believe that it could motivate people to try different key counts, specifically new players. There aren't nearly as many 7k players as there are 4k players, but almost everyone in the top 10,000 has mastered both, as well as most other key counts, at least to some degree. This is good of course, but considering that most people begin Osu! mania playing 4k, it can make it difficult for new players to reach their full potential.
I understand that this might seem small, but as a feature it makes a lot of sense because in game it's already possible for players to categorize songs based on key count. Feel free to answer the poll however you'd like, I won't personally be offended or affected if this idea seems silly to the majority.