The barge

Some countries are split in half by ideological division and some are not. Israel is an example of the former, NL an example of the latter. You are unfortunate if you live in a split country as politics is rancorous and governments are fragile. Leaving such countries aside, what you have are typically

green
liberal as in 'represents business'
Christian conservative
mainstream Socialist
far left
nationalist right party. 

Two or three of these parties will be able to form a block that commands a majority, and in PR that represents a majority of those who voted, so already an improvement.

I would argue that they produce better policy because they have to thrash out a way forward with politicians that they are working with but who are from other parties. So there has to be debate and compromise.

What you get from a FPTP winner is total power for 5 years to force through the whim of each single minister. Who does not even have to listen or respect alternative viewpoint over policy shaping. Hence you get massive costly blunders like

www.theguardian.com/politics/2019/mar/01/chris-graylings-five-biggest-failings

I think our system needs to be improved, then I look at the US and think could we be there is 30-40 years, with a total monopoly of the 2 main parties, and them spending time undoing what the other did.

Those that know me well, will know I tend to be Conservative. A little prone to tactical voting in elections, so last time in the local elections I felt the sitting independents were doing little for us, one seriously told me that "street lights have hidden cameras in them so the council can monitor people" another in response to a question on council tax said "I don't have time to answer questions from constituents" What were either doing as representatives of us the public.
When questioned by a friend on Councillors allowances (PAY) told her "it isn't much it only works out at £15 an hour"
I looked at the paper and felt that to get rid of the bad ones I had little choice but to vote Labour.
Labour took control of the Council from the independents

After the election when locally ( IIRC EBBW VALE) elected an independent, over the weekend he thought about his position and on the Monday became a Labour Councillor

for an example of how bad they are google silent valley waste.

But no way could I vote for a party ( whatever my natural leanings )
That bans abortion,
that isn't in favour of gun control, that believes the way to prevent mass shootings in school is to allow teachers to have guns ( I personally dread to think how the case where the teacher was shot by a six(?) year old would play out). Where people think it's OK to go shopping with a rifle over the shoulder, and a holstered hand gun.
Where getting seriously injured in a car crash runs a serious risk of bankruptcy ( one of my friends in the US has a serious lung condition , he was put in an induced coma in March time, he's now had a lung transplant, but is still in hospital, the last message from his wife was saying the Hospital stay is over $100,000 a week, and the lung transplant will cost $500,000, she said even with insurance etc the cost is so high he will have to go bankrupt).

Whereas here the parties can agree on some things, over there the divide is such that it seems if party A says bananas are yellow then B will say they are orange just to be different.

Unless I have the wrong end of the stick (which is entirely possible!), supporters of PR mean Preferential voting?

Well, there is an even fairer (arguably) and more "accurate" system, and it's called Proportional voting. Google it.

Under the moste excellente educatione I received in Oz in my formative years, the Proportional System was thoroughly explained to us and even then (age 13 or so) it made an impact and total sense to me.

I also understand (and the knowledgeable on here will again correct me if I'm wrong) that designing a fair, reasonable, representative and accurate Voting System is nigh impossible, it's a challenge that mathematicians have been trying to come up with a solution since the dawn of democracy. 

Sadly the American system should have an effective counter weight to the exstreams of the two party system that dominate there. It's called the supreme court and should stand up for the rights of the individual under the Constitution and bill of rights, but political stuffing of members into the court who can be controlled and have not acted in an independent manner as in the past has diminished the institution to a shadow of it's former past. The supreme court should be the final bastion of the democratic system and the rights of the individual over the excesses of politicians and parties, I think it's starting to fail.

there is already talk that Labour in Wales are fiddling the candidates for the next election.

The rules will be PR with Party lists, but a mandated equal number of male and female members

So lets say the top person on labour list is Male he is elected the the next candidate is Plaid their top candidate is male but under the rules you have to go down the list to find a female, the Labour again another man, then Conservatives scan down and find a female, then plaid again ah now the top candidate gets in .

it feels too complicated

The news item says 2/3 of members of the Senedd voted for it. So that is democracy innit.

Sheer madness when it's projected to cost £100m and you've already overspent your budget by £900m.

www.bbc.co.uk/news/uk-wales-politics-66438471

Assuming, for simplicity, 65m UK population, Westminster's 650 MPs administer the country at 1 MP per 100,000 people.

By that measure, the 3 million population of Wales requires 30 Senedd members.  We have 60, but apparently that still isn't enough and we really need 96...