I've kept an informal list over the years, inspired by 8222's aircraft log in the signature - I thought it may be worth us compiling a list.
I'll start my list (going purely off memory and it's not a completed list) and will add to it.
Im not including historic railways and anything I'm mentioning, was in commercial service. 
101 BR
104 BR

142 Northern* and BR
143 Northern* and BR
144 Northern* and BR

150 GW
153 EM
155 Northern
156 Northern* and BR
158 Various Inc BR
159 SW

165 GW
166 GW
168 Chiltern
170 Various Inc Central

180 GC and GW

185 TPX
195 Northern

220 XC
221 XC and Virgin

314 SR
315 GA
319 Northern
323 WMR
332 HExp
333 Northern
334 SR
357 C2C
380 SR

390 Virgin

444 SW
450 SW

800 LNER
801 LNER
802 TPX

43 Various in BR
91 LNER* Inc BR
(Also got hauled by a loco ahead of a 91, on a diversion when lines were down on the ECML. Unsure of type unfortunately. Was in too much of a rush to notice by the time I got off).

994 TWPTE and Nexus

1973 Stock London Underground
1992 Stock London Underground
1995 Stock London Underground
1996 Stock London Underground
2009 Stock London Underground
D78
S7
S8

B90 DLR
B92 DLR
B2K DLR
B07 DLR

Bombardier Incentro AT6/5 NET

Bombardier M5000 Metrolink

Bombardier Flexity 2 Blackpool
English Electric Balloon Blackpool
Brush Rail coach Blackpool

Foreign:
NSB EI 9
NSB EI 11
NSB EI 17
NSB El 18

Prague Metro 81-71

NS DD AR
NS Class 1600

Renfe 463

TIB EMU (81?)

*Inc previous franchise holders.
*need to add other misc stock
Will continue to try and identify additional foreign stock too*

(04 May 2022, 9:07 pm)Andreos1 wrote I've kept an informal list over the years, inspired by 8222's aircraft log in the signature - I thought it may be worth us compiling a list.
I'll start my list (going purely off memory and it's not a completed list) and will add to it.
Im not including historic railways and anything I'm mentioning, was in commercial service. 
101
104
142
143
144

HST
Class 91 / Mark 4
Class 142
Class 156
Class 158
Class 165
Class 166
Class 170
Class 180
Class 185
Class 220
Class 221
Class 315
Class 318 / Class 320 / Class 334 (unsure which in Glasgow was awhile back)
Class 319
Class 332
Class 333
Class 345
Class 360
Class 377
Class 378
Class 380
Class 387
Class 390
Class 800
Class 994 (why not)

Probably forgot something obvious but think that's it.

NRN classes:
43/HST (GWR/XC/VTEC/LNER)
91/Mk4 (VTEC/LNER)
142 (NR/ARN)
150 (TfW)
156 (NR/ARN/NTL/ScR)
158 (ARN/NTL/ScR/TfW)
165 (GWR)
170 (ScR)
185 (TPE)
195 (ARN)
220 (XC)
221 (XC)
365 (GTR)
375 (SE)
377 (Southern)
378 (LO)
387 (GWR)
390 (VTWC)
444 (SWT)
465 (SE)
700 (GTR)
800 (LNER)
801 (LNER)
803 (Lumo)
994 (Metro)

London stock:
1972 (LU)
1973 (LU)
1996 (LU)
2009 (LU)
S7 (LU)
B90 (DLR)
B92 (DLR)
B2K (DLR)
B07 (DLR)
B09 (DLR)
CR4000 (Tramlink)
Croydon Variobahn (Tramlink)

Edinburgh stock:
Urbos 3 (Edinburgh Trams)

(05 May 2022, 6:58 am)omnicity4659 wrote NRN classes:
43/HST (GWR/XC/VTEC/LNER)
91/Mk4 (VTEC/LNER)
142 (NR/ARN)
150 (TfW)
156 (NR/ARN/NTL/ScR)
158 (ARN/NTL/ScR/TfW)
165 (GWR)
170 (ScR)
185 (TPE)
195 (ARN)
220 (XC)
221 (XC)
365 (GTR)
375 (SE)
377 (Southern)
378 (LO)
387 (GWR)
390 (VTWC)
444 (SWT)
465 (SE)
700 (GTR)
800 (LNER)
801 (LNER)
803 (Lumo)
994 (Metro)

London stock:
1972 (LU)
1973 (LU)
1996 (LU)
2009 (LU)
S7 (LU)
B90 (DLR)
B92 (DLR)
B2K (DLR)
B07 (DLR)
B09 (DLR)
CR4000 (Tramlink)
Croydon Variobahn (Tramlink)

Edinburgh stock:
Urbos 3 (Edinburgh Trams)

Theres a lot more that could be added to this list, i might make a extensive version.

Theres also the T&W Metro Class 599's which are the 4 unrefurbished Metrocars

(05 May 2022, 10:31 am)ASX_Terranova wrote Theres a lot more that could be added to this list, i might make a extensive version.

(06 May 2022, 9:45 am)V514DFT wrote Theres also the T&W Metro Class 599's which are the 4 unrefurbished Metrocars

The point is what stock you've travelled on rather than a list of all the stock. There's loads missing there but it's not the point.

Just confirming that my list is for stock I've been on.

Haven't been on a "599" after they were "reclassified" so still 994s for me. Curious to know what their actual TOPS numbers are as the document that claims them to be 599s only refer to them as 40xx - the 4 being the end of 994.

(06 May 2022, 10:00 am)Storx wrote The point is what stock you've travelled on rather than a list of all the stock. There's loads missing there but it's not the point.

(06 May 2022, 5:00 pm)omnicity4659 wrote Just confirming that my list is for stock I've been on. 

Haven't been on a "599" after they were "reclassified" so still 994s for me. Curious to know what their actual TOPS numbers are as the document that claims them to be 599s only refer to them as 40xx - the 4 being the end of 994.

I'm sure wiki has a list of all the stock that exists. As pointless as logging your ridden stock might be, surely it's not as pointless as re-writing a list of all BR tops classes.

And just to clarify, mine is just that too.
A list of stock I've ridden.