Throwing my experience in here: if you have multiple hours a day to practice, I would choose the best performer who is also a good teacher. Every pianist will have a slightly different style and repertoire they click with. Someone who is intelligent and plays in a way that you find inspiring. Someone who is methodical and can strategize effectively.
Do you have a teacher these days
To find a good teacher, you need a good problem. A good problem is not "I can't play as well as I'd like to", that's too vague. A good problem is specific. Luckily learning the piano is full of these. Bring this problem to different teachers until one is able to solve it for you. Maybe it will be the guy with all of the accolades and university degrees, and maybe it will be some complete unknown.Good luck!
We could take it from another perspective. A student often doesn't know that they don't know. So a good teacher can reveal the important improvements and directions they didn't realise was important and the results of this produce desirable and noticeable improvement.And to the OP until your teacher no longer provides you with help and improvement I'm not sure if leaving is always the best solution even if they suggest it! The teacher may be overly humble and can certainly teacher higher grades, but if she truly doesn't have her heart into teaching that then it makes sense to move on.
This. Perhaps this is an opportunity not only to progress on your own journey, but for your present teacher who might need a bit of confidence to move onwards to more advanced students. If you are comfortable with that teacher and feel as if the direction and instruction you are given is worthy, why not make a pact to learn together with some of the assistance from the wonderful folks we have here to further the learning on BOTH sides of the spectrum? Your teacher will gain more experience and confidence teaching advanced students and you will benefit in the obvious ways from that relationship. I would encourage your teacher to take a chance. My $0.02…