I’ll start with the Porsche 997, the 996 looked alright imo, but it looks “like a 90s Porsche”, the 997 made it look sleeker and more modern. Still looks good today.
As for cars that looked worse after a facelift? Maybe the facelifted 6th gen Camaro? The 6th gen looked great pre-facelift, but they did something weird with the headlights and now it looks so-so…
The Aston Martin DB12 is essentially a facelifted DB11. I never loved the DB11’s front end, but I’ve finally grown used to it, and now they release the DB12, and my god, I can’t believe how the same person who designed both of those cars’ rear end (they look the same), and other models like the One-77 came up with THAT front end. It’s terrible.
And I know that what I’m about to say will be sacrilegious to a lot of people, but I often think cars that lose their pop up headlights look instantly better. For example, I always thought the original Honda NSX looked better with fixed headlights, even though the image of a pre-facelift model is undeniably legendary.