The company doesn't matter - only the mentor.
Companies don't provide good training, people do. Forget the name on the door and look for PEOPLE who can SHOW you a proven record of success and explain to you how they are going to help you achieve success.
In my opinion a meaningful mentoring program is one that supports marketing, interacting with customers, writing contracts, problem solving, etc. etc. and gives the agent a small slice of the pie to hold their interest.
The evidence of a good mentoring program will be in the statistical results. The average transaction count per agent of these offices will well exceed that of those companies who offer training with token mentoring. (they all say mentoring is available)
Until you insist on seeing the numbers, what you may be looking at is an illusion.
Best of success with this important decision.
Ultimately, the best thing to do is decide what is important to you as an agent and find a broker who is willing to help you achieve your goals.
I would be a bad fit for a new, inexperienced agent because I work with a high lead volume and would not be able to adequately train someone who was not a very sufficient, fast starter. Because of this, I feel that I could give you honest feedback and assist you in finding a company right for you if you wish. Feel free to contact me and I will help if I can.