Well in that case, I think they should go to Lumo, or perhaps they could be converted for the Bakerloo line
HOUSE!

Northern is the most logical place at this point as they could replace a sizeable number of the Sprinter fleet which Northern want rid of within the next 10 years
Logical to you, maybe, but I keep trying to explain that end doored 100mph trains are not what Northern is short of, especially as replacements for the (mid door, fast accelerating, 75mph 150s that are able to soak up passengers at Castlefield etc)
Before suggesting Northern as a dumping ground for any stock, I wish people would ask themselves “CIROTCLCS” (“could it run on the CLC stoppers” - i.e. the half hourly Oxford Road - Warrington Central - Lime Street trains), because that’s what Northern needs
Convoluted cascades that try to have 175s replace 158s so that those end doored trains can run on routes like the CLC just create more problems than they solve - there’s already enough “fast” stock, and 158s struggle when dumped on slow services to cover for the lack of 150s (we’ve already seen the problems of putting the 100mph on the Harrogate stoppers!)
They could either go to Longsight/Newton Heath/Ardwick and work the services to Barrow, Windermere, Chester (via Northwich), Southport and Clitheroe
Just because they ran to Barrow/ Windermere twenty years ago, people seem obsessed with reuniting them
Which Southport service; the one with twenty stops between Oxford Road and Southport or the one currently run by bi-mode trains due to the electrification south of Manchester?
Northwich and the Rochdale - Clitheroe services are both local stoppers
they could go to Heaton and replace 156s/158s on regional express services across the North East
If the numbers match perfectly then that at least ties a round peg to a round hole, given that there are no 150s etc in that neck of the woods
However I don’t know the PVR, and it’d be frustrating to have just a handful of 175s left over, or just a handful of Sprinters needed on top of the twenty seven 175s
Regional express standard stock (eg. 158s or 175s) is equally important on both Exeter-Penzance and Cardiff-Portsmouth and therefore the 175s wouldn't be wasted on either. It's just that I would tend towards 175s on Cardiff-Portsmouth and 158s on Exeter-Penzance (rather than the other way around)
It’s funny how all of your suggestions essentially boil down to “Wales gets end doored trains” (and other lines in the UK get the stock that you don’t like)
Northern are also reportedly looking for more ETCS-compatible units with the TransPennine route upgrade coming
Yes, it’s no secret GWR would prefer more Cummins 158s
Re the above two comments, it may be true that the managers running the day to day operation have expressed a preference, but they have no power, it’s all down to branches of Government and where they decide resources can go, there’s no “want” any more, there’s just what the unaccountable Government decide to allocate - we need to get used to this (even if it means accepting that mid life stock will be scrapped or some services will be culled)
The nature of the contacts mean that First/ Arriva/ Abellio etc are paid to do what the Government demand, there’s no point rocking the boat or making demands, it’s a case of “deliver what we tell you to, and wheesht”
Like with Brexit etc, this might not be the nationalisation that campaigners claim that they wanted but it’s the version we’ve got