IT IS HARD TO PICK THE BEST ONE,BECAUSE THERE ALOT OF GREAT ENGINES OUT THERE.I REALLY LIKE THE 72 SAITO.IT PACKS ALOT PUNCH FOR ITS SIZE.IT HAS A NARROW BEAM WIDTH,SO IT CAN FIT IN NARROW SPACES.
I ALSO HAVE SEVERAL MAGNUM 91 MOTOR.THEY ARE OS 91 CLONES AND HAVE BEEN VERY RELIABLE(HAVE GOOD POWER AND ARE CHEAP)
THE 70 OS I HAVE IS A SUPER RELIABLE MOTOR ALSO,BUT DOESN'T HAVE THE POWER THE SAITO 72 HAS(ALSO HEAVIER)
MY ALL TIME FAVORITE IS THE SAITO 91. TONS OF TORQUE,AND THE MOTOR IS VERY LIGHT COMPARED TO THE OTHER 91'S I MENTIONED.
HOPE THIS HELPS IN YOUR SELECTION
MERRY CHRISTMAS
PAULT
PS. I FORGOT ONE...THE NEW MAGNUM 61 MAKES A GREAT 4 STROKE FOR TRAINERS.ITS VERY SMALL...IT DOESN'T HAVE GOBS OF POWER,BUT STILL A GOOD MOTOR