Performance without a doubt. According to your profile you are in California so snow is not an issue for you, right? I have the Stealth and love the pure acceleration of the beast. I personally don't think FSD is worth it and after using AP for over a year I wouldn't fully trust it, with phantom braking and failing in difficult situations.
I know the new iteration of FSD is world of a difference but the subscription model is coming in 21' and you can always get that or add it at some point in the future, but you can't get a Performance without swapping cars down the line.