Choosing your agent

Hi
I'm hoping you can help and don't mind me asking...
I recently started working for a letting agent and have had a pretty busy couple of months but now am running out of "stock".
How do you guys and girls, as landlords, choose the agent you use?
Are you attracted purely by price or does the local brand/image play a larger part for example?
It would be nice to be able to say to the boss, "this is what landlords look for, this is what we need to be doing."

Any pointers and or input will be gratefully received!
Cheers
JB