Every political system has it weak and his strong points. The UK system is performing very well when the population is divided in two parts. Nowadays in many Western nations the divide isn't between two political forces any more (like the left against the right or conservative against progressive), but between more and more forces regardless the political system.
In modern society the nation itself became more important than the region. People are moving a lot, so a big part of the population isn't that much based in a region.
A mixture between regional and national you have in Germany (you have two votes, one for a party, one for a person, the total members in parliament do change because some are elected extra because the personal votes). France use two rounds for their regional elected ones when in the first round no one got a majority in a region. In the second round only the two with the most votes can stand.
There are many other interesting election systems, however it depends on the situation and the culture what is seen as the best. What I think is most important in a democratic system that the population do think it is a good system, whatever the system.