Euro countries have so many electoral systems (variations of proportional and majoritarian) that it would take me days to go through them all.
My personal preference is the proportional system - for obvious reasons. Those against it usually cite the near impossibility of a single-party government, which, according to them, leads to instability.
As far as single-member plurality systems (the UK, for example) I just can't see any fairness in the fact that one single party can have a majority of seats with only circa 30% of the voters behind it. Basically, 70% of the electorate represents a minority in Parliament. Go figure. Up here in Canada, they're toying with the idea of prop. representation. I am not holding my breath, though. The biggest losers would be the Liberals and the Conservatives. The NDP and the Greens would gain a lot.