There are way too many factors to consider when choosing a set of top x mangoes:
- Soil: mango flavor varies based on soil
- Year: mango flavor varies from year to year on the same tree
- State of Maturity: mango flavor varies quite a bit based whether it was picked too early or too late
- Time of Year: often, the first say 10% of a mango crop will be more bland than the later crop; for mangoes with multiple crops, late crop can sometimes be sweeter
- Culture of Taster: preferences vary widely based on the background of the taster
- Frame of Mind: placebo effect, first mango of season exuberance, etc.
- Climate: warm weather sometimes sweetens up
- Cultural Conditions: eg, postassium can sweeten up a mango
So, trying to compile a top x list is not going to be easy. Your best bet is to track someone down from your area who can give you some local advice and possibly some samples to taste test.
My "practical" advice -- you're in socal where you can grow an unconscionable array of ridiculously awesome fruits (cherimoya, persimmon, grapes, stone fruits, hass avocadoes, citrus, feijoa, pomegranates, etc, etc), so I would plant out one or two mangoes and fill the rest of the yard with all the other awesome fruits that you lucky brats can grow there.