It would be too difficult to name a favourite painting, I have too many favourites, though I tend to favour portraiture I think.
Here’s a wonderful portrait, La Velata, by Raphael. Raphael died at just 37, but he was an astonishingly prolific painter during his short life (1483-1520) and is regarded by art historians as one of the “holy trinity” of High Renaissance painters (the other two being Leonardo and Michaelangelo). He also, by various accounts, bedded a fair few women and the lady with the veil was Margherita Luti, his mistress of the time (about 1515).
It’s a strikingly sensuous and opulent portrait, rendered with exquisite attention to detail. It’s one of the sexiest painings of all time.