I disagree with whoever said they don't like the 365s, I think they're great for the Great Northern route, as far as Cambridge at least.
I find them vastly preferable to the 317s and 321s, which are probably my most disliked units. They probably aren't bad trains, they might even be good ones, but they've been given appalling interiors (FCC's 321 carriages feel like dark prison cells, and their 317 seats feel like they're padded with plastic) and have been grossly neglected, and many of them now rattle and shake alarmingly. I imagine that a bit of investment and engineering could improve the units drastically and give them a new lease of life, and this should be mandated by the DfT in the next round of franchises...
450s I like, when they are used appropriately, which they often aren't.