Every broker is different and different brokerage offices have very different atmospheres.
For instance, 1 office may be a young, energetic office while another may be a more formal, professional office even if they are with the same big brokerages i.e. KW, CB, ReMax, EH, etc.
As a new agent, the area that you probably need to focus on is education. While company caps and commission splits may be big factors, you won't have to worry about those 2 items if you don't actually LEARN how to do real estate, and getting licensed does NOT teach you that. I joined Keller Williams as a new agent and the education that I received has been invaluable.
There are several brokers who offer 100% commissions but will offer you absolutely no training, mentorship, or guidance. Many people think that Real Estate is easy, but its not. It takes time, money, energy, and a LOT of dedication. If you are going to "educate yourself" then it is going to be even harder to get started.
I would suggest that you interview at a few different offices of each brokerage in your area. Find out which offices offer the best in education and support. If you would like to speak with me about Keller Williams, I would be happy to chat. My cell phone number is 214-601-4192.