The avocados in stores are all Hass variety or almost identical variants (Lamb Hass). These replaced Fuerte variety avocados decades ago as they shipped better, gave more consistent yields, and the darkening skin gave consumers an additional clue to ripeness.

If you are interested in trying different varieties, there are many if you live in a growing region and have access to farmer's markets. In the US: California, Hawaii, Florida.

Depends on where you are in the world. In SE Asia, we get some wacky varieties that greatly vary in size, shape, and flavor. I bought a few at a local market in Indonesia that were border-line zucchini like in shape and had a very watery flavor.