My advice would be to go to a local dj store and listen to the speakers.
I dont think your mixing skills can be improved by speakers, your listening pleasure on the other hand can.
Personally i own a pair of KRK 6’s but i find them a little bass heavy for a small room.
I should have purchased smaller ones, thats why i recommend going to the store and listen to them first.
Most online shops offer refunds and the possibility to return goods.
You could use that option to try out different types 😉 ( just be carefull with the packaging )