It's not always about what mower has the better engine ,you need to make sure the clippings are dispersed from the discharge chute so
the mower doesn't clog with grass causing the motor to stall.

https://www.lawnmowerfixed.com/mower-chute-clogs/

There's always advantages and disadvantages over using a 2 or 4 stroke motor..


Cheers
Max.