If your looking for more torque and not crazy speed the best thing to look for in a motor is the number of. "Turns" ( windings around the magnet inside ) . You can get 20, 30, 45,55 even 80 turn motors. The more turns the slower but more torque a motor has.
Another thing to consider is hand wound. vs machine wound. I'm told hand wound are better due to the care and proper placement of windings and they are more expensive.
Then you have brushless motors but I don't own any and haven't done any homework on them.
Mario