Out of the ones I’ve lived in so far (and it’s almost all of them) I’d say Coventry. The UK in general is extremely expensive, and unless you have a really really good job, you’ll never make ends meet. As if this wasn’t bad enough, the weather is miserable, the women overrated (I’m being kind here) and there’s not much to do. Coventry was extra bad because of it’s design as a city, ugly due to the bombings and with a high criminality rate. Some people say Milton Keynes can be worse, but I wouldn’t know.
I’ve lived in London (exciting but extremely expensive), Edinburgh (bleaker than you may think), various parts of Greece (I hated it, but it’s generally not that bad), Shrewsbury (loved it, but I was too young to know), Copenhagen (great, but I didn’t need to work, that’s why), Prague (my favourite), Bydgoszcz (loved it, even though it doesn’t qualify as “pretty”), Zgorzelec (survived a year), Alkmaar (great city, but not for me), Berlin (nice city, horrible people) and Dresden (the happiest years of my life, but it’s not as good anymore). I’ve also spent a lot of time in other places, and I’m probably forgetting a couple. Coventry was certainly the worst.