Decisions, decisions!
I'm finding it difficult to choose an absolute favourite because there was a much bigger variety of vehicles on the go when I was a kid. When I was really small, single-deckers were Albion Vikings, Ford R-series and Leyland Leopards. There was a small number of double-deckers, consisting of a few ex-National Bus Company Bristol FLFs and some ex-Central SMT Fleetlines, but these were mainly used on school work and were rare on service work.
Of the three single-deck types, it probably has to be the Viking that stood out. I didn't know what each type was at the time, but the Viking had a particular howl that I liked. We moved house in 1980 and I was able to walk to school after that, so travelling on them was no longer a regular occurrence. I remember seeing them bringing kids to school from the neighbouring village for a while, but their days were numbered by then. The T-type Leopard was also notable, probably because it was different from the usual Y-type and Duple Dominant vehicles that er... Dominated!
Going forward a few years, I developed a fondness for the Alexander P-type. I realise this is a divisive issue and that they're not everyone's cuppa, but they were new, more modern-looking and not Y-types! ND6 (A506FSS), a Dennis Lancet with the Perkins V8, almost became the dedicated bus on my route for a while. This one has actually been preserved, fortunately.
The other P-types were on Leyland Tiger chassis and, while they were a relatively rare sight in the beginning, they certainly made an impression. NBT16 (A116ESA), one of the TL11-engined examples, eventually became a fairly regular sight. If i was pushed to choose only one favourite, this would have to be it.
If I'm permitted a favourite coach, NCT1 (KSL41X/1412NE) has to be it; formerly a Dominant III Tiger which was obtained for the Aberdeen Football Club contract, it was rebuilt with larger windows and up-seated to become part of the regular fleet. It had a 6-speed ZF 'box and went like you-know-what off the proverbial shovel.