Perhaps a new aspect to this would be your least favourite liveries?
I vote for Colas rail livery
Ah well 56312 in that horrible all over purple livery with bright green text,
The NX livery together with WAGN liveries.
Must say though the 365s in the NSE livery but with FCC branding was the best design at the time, pity no TOC does the same with one livery being used and just have a vinyl in the middle of the coach denoting the TOC which would have been a lot more smarter then some liveries currently in use ie East Midland Trains running 158s with Transpennine Express, Central Trains and East Midlands Trains logos/branding etc...
Would save so much money when franchise renewals come up as well, the same could apply for stations with one basic design used for InterCity, NSEn