best fuel option - 100LL, 10% Eth, or Mix

In my area, I can fuel my Rotax powered airplane with:

1. 93 Octane autogas with 10% Ethanol

2. 89 Octane autogas with no Ethanol, or

3. 100LL Aviation Fuel.

4. A mix of 100LL and 89Ethanol Free.

What is best for my Rotax 912ULS considering short term performance and long term operation?

Can I mix 75% 89 Octane and 25% 100LL for 89x.75+100x.25=91.75 Octane and have the ideal of <30% leaded fuel and Octane >=91?

Thanks.