My best flight? Can I have two? The first flight I ever made, when I was around seven and the family was off to Spain or somewhere like that on a Clarkson's special. I can't remember anything much about the aircraft type, but I do remember that on landing various bits of the engine hinged out -- "Oooh, look!" I shouted loudly. "The engine's coming apart!" Cue much discomfort among surrounding passengers, and an announcement over the PA a few minutes later that this was a perfectly normal part of reverse thrust.
The other best one was a few months ago, when my retired country parson father took me up for the first time with his brand-new PPL in the somewhat less than brand-new flying club Cessna. Terrific fun, even if... well, families must have their secrets, eh?
R