Welcome to Just Answer,
Your symptoms could be coming from either the brakes or the suspension.
Causes for a brake pull,caliper piston seizing, caliper slides sticking, or a brake hose restricted internally. typically the problem will be found on the opposite side of the pull (not working correctly the "good" side takes over).
To diagnose the brakes lift the front wheels off the ground and attempt to rotate the wheels and see if one is hard to rotate, If difficult to rotate try prying piston back, if it won't move crack bleeder and see if pressure is released (restricted hose). If no pressure release and piston won't move caliper faulty. check caliper hardware for binding, caliper should "float" and move from side to side.
If nothing found with brakes, inspect a lower control arm bushing or ball joint for wear and movement, also check all suspension components for wear.
Any more questions or if unclear please just reply back.
The already tried part of your question has just shown up.
Is the pull just a dip then it straightens out? Or is it a pull that you have to fight all the way through a stop?
I noticed you stated new Rotor not rotors was the other rotor resurfaced and what were the conditions where you just needed 1 Was brakes worn much worse on one side than the other?