Youre giong to get a hundred different opinions from a hundred different people, it's more of a matter of opinion of which engine is the best, pretty much any well known brand is going to be a great mill, some will hate certian engines that others love. As far as what you want the engine to do depending on track layout, the gear ratio and venturi inserts can aid in tuning the engine down or up for he most part. Good luck on your decision.