You are buying an engine to match your fuel? Forgive me, but usually I buy fuel to match my engine. Is there a reason you are limited to FAI fuel? I have found that most small engines run best with a little nitro. But, whatever!

From that list I would get the O.S., mostly just for the ease of use. Next I would get the Enya. As for glowplugs, I use an O.S. #8 or a #A3.