Do you want the most powerful and highest quality, or the most "common"? All the engines mentioned will fly this airplane just fine- the YS-1.10 is the best quality and strongest of the engines mentioned....

Heck the OS-91FX has plenty of power for "most" people (if you can find a good one-) I would probably opt. for the Saito-100 since the YS is soo expensive---

I cannot imagine having problems with the Saito, they are generally considered mild-mannered engines that are easy to tune/run/adjust--