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…
AU Falcon had a weird grille, AU2 went back to something normal looking
AU https://en.wikipedia.org/wiki/Ford_Falcon_(AU)#/media/File:1998_Ford_Falcon_(AU)_Fort%C3%A9_sedan_(17196313703).jpg
AUII https://en.wikipedia.org/wiki/Ford_Falcon_(AU)#/media/File:2000-2001_Ford_Falcon_(AU_II)_Fort%C3%A9_sedan_(13897447116).jpg
Unfortunately it took another generation to get rid of the weird shaped Taurus inspired windscreen