I would like to focus on something that will certainly go against the majority of the opinions.
I know that we are talking about fantasy worlds and that different races are one of the most appreciated topic, but I always found that "too much is not always too good".
There's a wonderful idea, already developed and played, that is called Starfinder, so I was thinking: why can't we have the same thing in the medieval ages ? Instead of filling the basic setting of Golarion with tens or hundreds of different playable races (which often are not even sufficiently described, and even less coherently played) wouldn't be better to think about secondary settings, on different planets (just like in Starfinder, but always in medieval ages) in which to insert the various "minor races"?
For example, I see many people talking about Catfolks and Ratfolks, why not to create a planet with only anthropomorphic animal races!? And this is just one of the many ideas it could be could think on.