Help choosing motors for meccanum drive robot

Hi,
I’m building a 3d printed robotic car with a meccanum drivetrain. The robot is currently 25*15 cm, is driven by four TT gear motors 1:120, the wheels are 8 cm in diameter and the robot weighs 1kg.

I am looking to use some new motors, because the old ones do not output enough torque, are hard to mount with screws and run off 3-6V. I want a 12v motor, but I am not sure about the RPM. It has to move the robot at a descent speed and be as cheap as possible . Based on what I have read other places 80 RMP would be a good choice (?), but I do not know if I have to take the meccanum wheels into consideration (because they do not have that good traction)? Any suggestions, links appreciated

The motors I currently use:
(https://www.banggood.com/no/4PCS-DC-3V-6V-DC-1120-Gear-Motor-TT-Motor-for-DIY-Arduino-Smart-Car-Robot-p-1567910.html?rmmds=detail-left-hotproducts__4&cur_warehouse=CN)

Hi,

I suggest you to take a look at the following tutorial to help you selecting motors: