
I grew 3 types of eggplants last year.
I grew the Casper variety, which is supposed to be early. I don't know as I was in Texas when they would've been being early. They are white and I got my seed from Seed Savers Exchange.
I grew Rosa Bianca cause they are pretty. No other reason really. I got that seed from Fedco.
Also from Fedco, I grew Diamond eggplant, an open-pollinated black eggplant. Basically, I was unsure I'd like the white or rose colored stuff; always get black at the store. So this was my backup eggplant.
Here's what they looked like...

basic experiment
I use most eggplant in eggplant parmesan, some in moussaka. While yummy, I didn't think I'd be able to distinguish varieties in those dishes.
So I did the simple thing; I just stir-fried the eggplant in a bit of olive oil to see how they tasted.
To my taste buds, they were absolutely identical. I mean, I just flatout couldn't distinguish them even with eyes wide open, they taste the same.
So what am I growing this year?
Diamond, Casper and Rosa Bianca.
I had leftover seed, so started some of each in late February; moved them under lights a few days later once they germinated. If I'd not had leftover seed or if some hadn't started, I'd have ordered more.
Why not? They're all pretty. I enjoy beauty when working in the garden.
As nightshades, they may or may not be susceptible to blight, which my tomatoes had a bad case of last year. So I see no reason not to grow multiple varieties in hopes that one or another may have various resistances.
So the verdict is: all of them.
Image credit: Stirfried Casper, Diamond and Rosa Bianca eggplants.