I'll miss the 747. Sitting upstairs in one is a far nicer experience than anything you get on an A380 or 787. And the refurbished airframes that were updated a few years ago were certainly no worse than many of BAs 777s.
Most memorable flight for me was flying into Joburg about 15 years ago in what was already a very very tired airframe. Sitting in the front exit row of premium economy where the carpet was soaking wet because the plumbing to the washroom was leaking! And then, a go around from short finals to land at Joburg because the flaps refused to extend to the full degree required for landing, followed by 30 minutes of flying around the countryside with the crew trying various mild positive and negative G manoeuvres to persuade the flaps to lower, which eventually worked. And a typically apologetic BA Captain telling us the flaps weren't working due to the age of the aircraft!