Here’s my way to judge the best avocados. Best tasting isn’t the right question because so many taste similar. So you need a different way of thinking about it.
I’m in 10a and can grow any type. The categories for me are:
Guatemalan, Guatemalan x Mexican, Mexican, Guatemalan x West Indian
Most people consider Guatemalan the best tasting. If you don’t get below 30F then you can grow anything and should grow a Guatemalan or Hass type that does well in your area. Nabal, Jan Boyce, Reed are not different enough to pick one solely based on flavor. But Reed stands out as being fast growing and productive.
The next tier down is 25F range. Bacon and Zutano are reliable and taste good if left on the tree about 2 months longer than most people pick them. There are a lot of options in this cold hardiness range. Many claim to be like a Hass but of course they are a notch down.
The Mexicans are super cold hardy and grow very fast here. I like to see things happening quickly but I haven’t tasted them yet. I have Mexicola, Duke, Aravaipa and some others.
The Guatemalan / West Indian I have are Lula, Marcus Pumpkin. The West Indian genetics make them grow fast but mixed reviews on taste. I’m not sure there is a good argument to make for these in California.
I think it’s really best to make these groupings and assess how an avocado compares to others in its class. I would start with your hardiness bracket and pick a good tasting and productive type in that group.