I think the XC 170s are quite poor just due to the legroom alone. I’m 6’1” yet literally can barely get my legs in the airline seats? Much better if you can get a table or a vacant priority seat but these are often occupied from my experience.
I also don’t like the Voyagers - I find the seats uncomfortable and the vestibules still smell like toilets. They are OK other than that though.
I like the 180s based on comfort and overall passenger experience, but they’re a poor train based on their reliability record alone.
There are other trains that are a bit dated like 150s and 153s, but I find it is often more down to the routes they operate. I find 153s perfectly fine on the Heart of Wales, and 150s adequate for the Valleys, Devon/Cornwall branches or Exmouth to Paignton services. They however aren’t adequate when they substitute on Cardiff - Manchester (and when they used to substitute on Cardiff - Portsmouth/Brighton runs).