Best: By some margin I think getting an upgrade to First on a 12.5 hour trip back from BKK last week, and not only that but it was an excellent first First experience with a great crew

Worst: One of two things really - A non-functioning CW seat on a very full return from GIG in September (but it was an excellent trip so I was in a good mood and took it in good humour despite the less than perfect experience - crew handled it well too)
OR, between SYD and BKK (prior to mid-journey upgrade) being chased up the stairs and accused of taking more than one CDM "bar" from the kitchen (I hadn't). I'd have definitely been more pi**ed off about this and the lack of subsequent apology had the second half of the journey not been such a pleasure

On balance and from a lot of flying this year (75% or so on BA) the experience has far more often than not been in the "best" camp I'm pleased to say!