Zenoah has been around in the aircraft engine departmet for about the last 20 years while Brillelli has been going at it now for about the last year and a half. You won't get hurt either way. However, you could buy a less expensive 26cc engine than either of them sell and get hurt very badly. Currently Zenoah, Brillelli, and 3w are three top of the line engines in the size class so pick one and enjoy. The 3w is more expensive.