I've used avocado oil, walnut oil, extra-light tasting olive oil, MCT oil, and coconut oil.
I think it depends on what you want to use it for. I didn't like the taste of olive oil mayo, even with the extra-light, so I only made it once. I did try a half-olive oil, half-coconut oil combination, which wasn't as bad. With avocado and walnut oil, it's great for making salad dressings and other flavored "sauces". For tuna salad, chicken salad, BLT-Bs (bacon, lettuce and tomato minus bread) I prefer the MCT oil mayo--MCT oil is tasteless, so it doesn't "contaminate" the other ingredients. Coconut oil works great so long as you use the whole batch at once; the coconut oil gets hard in the fridge (harder than olive oil) and then the texture isn't right.
I make a 1-egg yolk batch at a time, and it makes about a cup of mayo. Hubby and I usually eat that up in 8-10 days and it's lasted fine in the fridge.
You make your choices, and you live with them. In the end, you are those choices.
"Strength is the mental and physical fortitude to endure, resilience to bounce back, and force to create change, allowing you to thrive in any circumstance and through any adversity." TrPAssassin