Cardiff is probably the most disproportiately inexpensive for it’s location based on my non-scientific observations… Not many new houses so most have been owning for a long time so they can afford to rent stuff out at attractive rates.. It may have been an anomoly the few times I’ve looked and lived there, but it might be worth checking out…
On a side note, I felt that people were also abnormaly unfriendly in Cardiff! That might be a personal experience as well!