Are you asking as a new agent, or an experienced one?  There can be differences depending on this.

Hi Jennifer Dressel.  First, I'd say ask this as you, not as anonymous.  There is no need to hide your identity since this is a school question and not about an active transaction. 

Since you are a new agent, I'd say one that can train you properly.

 I would choose a broker that has a good training program because you don't even learn half of what you're going to have to know to be successful a real estate ...

Great answers here. I hope you got it. 

Now Paul is a real estate novelist
Who never had time for a wife
And he's talkin' with Davy, who's still in the Navy
And probably will be for life

Call me, we can talk about a great company to work with.

Rachelle Surrency has the answer!

I value a friendly, supportive culture with ongoing training and accessible leadership.

Training and availability, and of course someone you just like.

New agents should look for good training, someone who will take time to show you the ropes, high integrity, etc.

As a new agent - finding a knowledgeable broker who is accessible.  You should be interviewing them as much as they are interviewing you.  Good luck.  

One quality is that the broker is a teacher and has the patience to do it.

A good mentor if you are new.

Integrity and support.

Everything. Interview with several.

Jennifer, Rachelle Surrency nailed this one!

The best - if you are a new agent - education, training and mentor-ship.

If you are in the business for a while, support mechanism from the office and split.

I wrote a blog on this a few months ago that's becoming an ActiveRain classic.  

One that will mentor you.

Willingness to mentor

The good ones.

You have to go on reputation, integrity and what the broker will do for you in the way of training, time and the future.

Availability and Mentoring skills

The broker has a photo and a name on his website.

Training

Find someone you like, that has a good training program for newbies.  A

Find one that will offer you a mentorship or training program. 

One who provides the services you need.

Its like choosing a friend only with a broker, its a conditional relationship. You both give to get and money drives the bus. It is my belief that they are responsible to nurture, train, guide and educate. You are to Q & A & work it

See Rachelle Surrency comment.

Someone who is accessible, and is willing to train and mentor you, or offer training and mentoring opportunities

training and mentoring....you won't have much interaction with the broker/owner.... 

Rapport and a good mentoring and training program.