I respect all views on this Tesla/Panamera conversation, and hope mine is respected as well.
To me, the Panamera superbly combines the 911 "sports car" dynamics with a luxury sedan. It handles--regardless of its weight--as well as most sports cars (including most 911s), yet provides extremely high quality luxury, design and sophistication.
There are certainly sedans--Tesla, Audi, Mercedes, etc.--that may be faster in a straight line, or be a better "bargain", but none combine performance (another word for race bred engineering), luxury, and design better. And that combination is where Porsche has always excelled. My 911S in 1969 was not as fast as a Camaro or Dodge Hemi, but the sporty combination was so much better.
I will throw in another intangible, which affects my preference for Porsche products--the brand's decades long commitment to racing. That commitment gives me a sense of pride and confidence, which I am willing to pay extra for. Porsche is nothing without racing--and the engineering advancement resulting from it.
One final comment. It seems to me that Porsche should be given more credit for extremely high build quality. My current Cayenne Turbo impresses me every day with its fit and finish, inside and out. And my recent experience (yesterday) in the cabin of a new Panamera Turbo, confirms by admiration.