Others may disagree, but I am all for “competition” - I am a realtor, and would not make any of my buyers sign any “agreements” that will tie them to me - how can I? If I don’t do my job, then these poor people will be homeless. The most I would ask for is, if an agent shows you a particular property, then by all means let them write the contract for you - that’s the only way they get paid. Don’t go behind anyone’s back, let them know you may be working with other agents but that you “really want to find someone I can work with consistently” - the good ones will float to the top, and will work hard to earn your business. Most agents are steered away from investors by their brokers, so I would try to find an “investor-friendly” realty company.
I don’t sign Buyer’s agency agreements with anyone. You need to maintain a level of integrity yourself and make sure that you bring the deal to the realtor that finds it for you.
As long as you are buying homes from them they will bend over backwards and continue to pull listings for you. If you constantly have them pull listings but never buy, they make no money and there motivation to help you will dwindle very quickly.
I always make it a point to make a few offers withing 48 hours of my first contact with a new realtor. Hopefully one gets accepted right away. You have a loyal realtor after that.