I myself am fairly new and play mostly empire. I enjoy the do-it-or-die challenge and brutal cunning and violence of sith and imperial anything in general.
However, this thread is sounding a lot more like irl politics than a game all of a sudden
Would I want either of these for an irl government? I think not.
The Empire is evil.
It is run by Sith, who are of the dark side, love war and violence, started this war that has killed needless thousands (even of their own), they are expansionist at heart, did I mention evil?
Now, if you were to replace all the sith with your hypothetical phlosipher king as you suggest, a sort of completely un-corruptable (didn't you mention that the senators couldn't resist their smaller
ever-present lure of corruption?) who could out of the sheer goodness of his heart punish all the evil and leave only good. Yes, then you would be completely fine. However, if we are talking irl, I seem to not remember any fantasticly perfect dictators...
In the Empire, you can do whatever you want as long as it helps "the Empire". So if you're a slave, well I'm sorry, not only do you have poverty, little upward mobility, and poor conditions: here enjoy this slave driver, family destruction for convience, and zero freedom to decide at least how
you will live your sad life.
Lastly, in the Empire, does it seem all that likely that someone who has the freedom to punish or kill their subordanates at will will really be nicer than someone held to standards of respect (not just effectiveness)? I seem to remember nazis having the same freedom, they were nice...
Now to the Republic.
The Republic has a decent representative system but as far as I can see lacks any real jusidial mechinisim. It has a representative main body, but each of those folks come from largely monarchical or other planets (which seems to be where you pointed to for a lot of your objections)
The Jedi Order you could claim are close to judges. Personally I don't want a cop and a judge to be the same person. That also has a nagging corruption tendacy. "This guys punched me in the face bring him in, I'm sure he stole that car too." Jouries anyone?
Also, the fact that there was no clear executive power in the Republic is what seems to have allowed the Palpitine to take over so easily when they (the senators) needed quick action. No, the Republic is very much a hob-gobled conglomoration of various systems held together by a few decent (not perfect) souls as well as a bunch of wannbe monarchs who ONLY seem half decent because they don't want to be thrown out and get away with whatever they can. (However, the idea of a representative system at least attempts to limit this). They certainly have poor, but you can't eliminate poor by force without just using up untold time and resources taking away from anyone who has more than someone else. The Republic and it's monkish cult of Jedi aren't up to standards for a real life government, but then again, nobody should expect them to be. It's an idle-ised story after all.
I would conclude by pointing out that empire-is-really-best-for-everyone folks seem to be looking for the exceptions (but there is this nice empire group over here, and look, this guy earned his rank with honor and effecency) (but this republic guy was so corrupt, look at this shadey deal!) while the republic-is-the-true-hope certainly make generalizations that are not, and can not be, always true.
I am confident that you all understand that this game has been carefully balenced to allow upperward mobility and power for all classes (a real sith empire could not be rated 18 or under, or within sane decency for that matter). These factions are the product of storywriting and of course the writiers will bring out very unlikely good elements from Empire and evil elements from Republic. That's good and not boring story. Niether of these factions should be concidered as slightly feasible irl. Light side dark side anyone? Keep it simple. It's fun.
Irl politics are confusing, messy and take more than hypotheticals. They take history, insight, and fundamental princiiples.
As for me:
I play to continue enjoying and loving my sith inquizitor, who zaps everyone, schemes regularly, and generally does evil in a very PG and unevil, lulz way.