Have to say the 317s with the fairly low back seating that feels like you are sitting on the floor are well past their best and need to be sent to become razor blades as soon as possible, the ex Stansted ones are slightly more tolerable but need to be sent to razor blade factory soon too.
As for the 321s, the ones without the Renatus upgrade can be a mixed bag, I was on two yesterday and one was in excellent condition and the other one was a bit of a heap. Yes the seats are poor angle and the PIS can be unreliable and the bad ones really are lacking TLC, but can survive for a couple of years more if needbe and there are no other major problems. They do what they say on the tin and the good ones are a little more steady over the tracks than the Renatus, even if the one I was on last night was very lively.
Now the Renatus units just scream cheap, crap, poor build quality refurb. I have to say that they look nice, and the seats are an improvement. However the AC is crap, the same crap PIS, the lights are overpowering, plug sockets never worked from day 1, ride quality is worse, especially in first class (which has a shocking layout) and doors unreliable. The Renatus upgrade is a big example of style over substance.
For the EMUs on the franchise I'd go
- Class 360
- Class 379
- Class 321 (original)
- Class 321 Renatus (if build quality was better and AC/socket worked it'd be 3rd)
- Class 317