When I choose one kind of the Ranking table what I wanted to view,I often fail and click more than two times.So I think that using buttons would be easier to change the Ranking table.Even though this feature seemingly had been used before I started to play osu in 2012.
Of course,if the icon of Country Ranking's button is user's national flag,that couldn't be better.In addition,for being the general players,I prefer to see the Local Ranking and the Global Ranking on the left side.