Well being from Europe I know a lot about European history and if I had to be honest a monarchy unites the people while a republic has the opposite effect.
I'm also from Europe (England to be exact), and I like to think I know a bit about history as well

I wouldn't necessarily say that unity has always been the case under a monarch, particularly today - England is incredibly politically and socially divisive right now, as have many other nations with a monarchy in history.
You look at countries like the Kingdom of Sweden, Denmark, Netherlands, Norway and they are among the happiest countries in the world with the lower crime rate.
As Caleb said, very simplistic to just say that this is due to them being a constitutional monarchy. Iceland, Finland and Switzerland are also some of the happiest countries on earth according to the World Happiness Report (higher than the Netherlands and Sweden in fact), and they have been republics for some time. That doesn't mean then that all republics are good, and all monarchies are bad (even if I do inherently disagree with the system), it means that there are more nuances and issues that must be considered.
According to your logic, I could make the exact same argument with socialism - Denmark, Sweden, the Netherlands and Norway have all embraced a more socialist system of governance, and are some of the happiest countries on earth, therefore socialism 100% works, without considering the nuances (I'm assuming given your stance on monarchy you would not be a fan of socialism, forgive me if I'm mistaken).
Greece was a country which was much stronger politically and economically when it was a monarchy compared to a republic.
Again, this is too simplistic. Fails to account for problems with the EU and the euro, and poor financial management on the part of the government. Being pro-republic doesn't mean being pro every single government that exists. Shit governments exist, as do shit monarchs. America and Russia are some of the most powerful countries in the world, politically and economically - both of them are republics, and are fairing better than when they existed under monarchical rule (this is subjective, though there are definitely problems with their governments, some of which are VERY severe, and great income inequality definitely still exists, the overall standard of living for the general population has increased since getting rid of their monarchs).
I just heavily dislike republics as they encourage division and people don't have a figurehead to look to for accountability. It's always 'blame the opposite political party they screwed up vote us in and we will fix the mess they made' instead of the people and the head of state getting together to discuss the issues and what can be improved on and what needs to change to represent the majority.
That'd be all well and good if you could guarantee that the person BORN for the role, rather than elected based on merit and experience, could do the job effectively. But you can't guarantee that. In my opinion, that is why I think monarchy is silly and reckless - you shouldn't give someone such an important position just because their mum and dad held the same position.
I'm not saying that democracy is fool proof - hardly, there are A LOT of issues. But there are a lot of issues with monarchies as well. What happens if the monarch is apathetic about the position, and doesn't really bother (eg. Tsar Nicholas II). What happens if the monarch is cruel, stupid or power hungry (eg. Kaiser Wilhelm II). Even in if it was a constitutional monarchy, and their powers are limited, if they don't do the job well, they shouldn't have the job. Furthermore, there is still very much so blaming of opposite political parties, and pleas for votes based on the incompetencies of the opposition in constitutional monarchies. Look at England! I feel like half of the news is just "Corbyn did this" and "Tories did that". The Queen is so far removed from the political system that nobody holds her accountable at all, not because she is doing her job well, but because really she doesn't have much of a job anymore. As an english person myself, I can say first hand that the only people I know that actively the monarchy are a few elderly individuals I know (mainly my grandpa). Other than that, everyone I know, from family, friends and aquaintences either dislike the concept of the royals, or are apathetic towards them.
Besides who do we like better the queen or Tony Abbot?
I'll take neither thanks. Besides, the Queen didn't even want to be the Queen anyway. Tbh I genuinely feel sorry for her - so much stress and heartache for a job that really doesn't need to exist anymore (imo).
Goodbye from Russia! (where it gets dark at 5pm so I need to find threads like this to pass the time

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