Yeah, the UK voting system is bad. I blame Brexit in part on that system.
I think New Zealand and Australia have probably the best systems of any democracy - but that doesn't necessarily correlate with the quality of politicians.
Let me give you another point of view.
I do not believe Brexit was a result of the UK voting system but a result of populist BS and a BS referendum where it was not even clear what was being voted. If it had adhered to UK voting system it would have been discussed and voted by MPs in Parliament.
Western style democracy is a fantasy where the common people believe their vote really counts. I have not voted for decades because I believe the entire system is rigged and all politicians and parties want us to play their game. I look at soccer teams. Of course they all want to win but the fact is they have their tournaments of this and that and they ALL live off of that. It does not matter whether they win or lose it is still their business. It is better for them if they win but they do not care too much if they lose. What they do care about and what would scare them is if people stopped watching soccer and started doing something else.
Politicians would like to win but what they really want is for the people to support them by believing in the system, in western style democracy. But the fact is the common person has no say and no input and he is just asked to vote for candidates others in power have elected beforehand. It's a con game.
Also, the political system has little to do with good government. A bad political system can be made to work with a people who are responsible, moral, working, well meaning, etc. and the best political system will fail with a people of liars, cheaters, scoundrels, corrupt, thieves, etc. We do not have to change the political system as much as we need to change ourselves.
You look at the British first past the post system and see its shortcomings and indeed it does have them. But then I am in a country with more of a proportional representation and it is far worse. In UK at least politicians answer to their constituents but in Spain they answer only to the party that nominated them.
Spain has been changing political systems for over two centuries now, always looking for a better one but never finding a suitable one. Not realizing that the problem is not the political system but a people and a culture of corruption, liars, scoundrels, thieves, cheaters, immorality, etc. There is no political system that can work with a people like that.
One of the stupidest beliefs of western people is the dogma that western style democracy is an absolute value above everything else. Then we are surprised when we invade countries with the ostensible intention of installing democracies and it never works. Of course I believe the real intentions are others and never spoken out loud.
The UK system has worked well for a long time and if it is not working so well now I would ask what has changed rather than changing the system because you might be surprised that the new system is worse than the old system. And the new boss is the same as the old boss.
UK has worked well by adhering to tradition, convention, respect and making an old system work. I would tread very carefully because you might discover things can get worse.