Which is better - 90 octane no ethanol or 93 octane 10% ethanol

Up here in the great white north our 87 and 89 octane has "up to 10%" ethanol, but the high test (91 and above) has no ethanol.

For me, if I'm going to use the gas relatively soon I'll just buy the cheap stuff. I run the 87 octane at normal fill-ups, but when I'm putting the car away for the winter I always use the non-ethanol gas plus a bottle of stabilizer.

Whenever I fill a gas can (for the snow blower, lawn mower, weed whacker, generator) I always use the high test plus stabilizer.

So if I had your options I would go with the 90 octane, no ethanol. Unless you NEED the extra octane to prevent detonation.