DMU: Class 150
EMU: Class 317
Diesel Loco: DB BR218 (Or if it has to be British, Class 57)
Electric Loco: RhB Ge 4/4 II, or if it has to be standard gauge, DB BR143. (If it has to be British, Class 87)
Steam Loco: GWR Manor
Tube Stock: 1967/72 Stock
There was a time when 58s on passenger were relatively common. Just go to New St on a Sunday morning when the Nuneaton drags were on and you stood a reasonable chance of getting one. I picked up 4 different ones in 1988 in 3 visits. 56s were rarer, never had one of those on the Nuneaton drags, but they did work them.
My favourites - 37 on Mk1 SOs
Baby GMs on Cravens
Trans Pennine/Swindon Intercity DMUs
Class 309 EMUs
For more moderm stuff, I have to admit that 375/377s (2+2 seating sections) are very pleasant to travel in. 185s are pretty good too, just a shame that they're nearly always overcrowded.
Its all about the Class 43 HST, they're where its at!
I also like 56s/57s
Steam, well I like the LMS Stanier Coronation Class* (favorite being 6251/46251 - City of Nottingham), Stanier 8Fs and Fairburn 4Ps. The Peppercorn A1s and Gresley A3s from Late and Never Early but not as nice as the LMS locos
Diesel - class 40 followed closely by class 52 and V200s (except it was the other way round as my trainspotting started in Plymouth and went from there - ).
DMU - class 126
EMU - 4 REPs, Clacton units or OeBB 4061
Electric - Roarers or SNCF 40101 class
Steam err QJs (can't beat riding in the cab of the rear of two QJs pounding up the Jitong line with a heavy freight in tow especially as I nearly managed the perfect murder - the missus was not impressed) but also WC and MN Pacifics
Sadly - All these are just a memory (except for the missus - she hasn't been condemned and cut up yet).
Diesel- class 47 and 37's Leccy- class 92, remind me of the 81's and 85's sound wise hate HST's, valenta or mtu, Replaced a load of loco hauled turns, NOT LEAST THE DELTICS and the loco hauled trains from Newcastle to Poole/ Paignton in the summer, the York-Plymouth turn, replaced by a tram, even worse the bristol-newcastle-birmingham was replaced by the stomach turning voyagers. I have to admit though, these days I'm more inclined to take a tram than a 91 or A voyager, though it still rankles, old habits die hard. Even worse I've noticed theyre using trams for rail tours, NIGHTMARE!!!!! DMU-not hot on any dmu but taking a 156 is certainly more comfortable from newcastle-sunderland/carlisle than a mobile bouncey castle that was/is a 142/143 EMU- like the dmu's sometimes a necessary evil, especially when in the smoke, the DLR is particularly galling, reminds me of the taxi's in total recall, i found most of the EMU's very samey, the slam doors were canny i suppose.
I seem to remember doing this before somewhere, but giving it some judicious thought..
Steam: Britannia or Hall.
Diesel locomotive: UK: 50. Overseas: M62 or 2TE116 (which I've only seen on YouTube, but sound amazing). Or anything with a supercharged EMD 567 or 645.
Electric locomotive: UK: the 86s and 92s probably sound best
Overall: SNCF BB 7200/15000/22200, or Taurus for the sound.
Diesel MU: Class 221, for performance & sound, and I think they look better with the outside frame bogies. And have (a few) more Seats
Electric MU: 442, or an old skool CIG with the nice deeply sprung Seats. Or overseas: ICE3