Ok, first of all, we are equating Jedi and Light Side here. Take that as a given, but if there is a distinction it might become relevant later.
The Jedi believe in what they call the Light Side of the Force... to be more accurate, they believe in following it- they don't have to bother belieiving in its existence, they can feel it, and they can feel the Dark Side also. The Light Side is about balance between all things- not a neutral Galaxy where there is as much evil as good, that is not how Georhe Lucas sees balance, but instead a Galaxy of peace and harmony. Of course, the Galaxy is not one compsoed just of stars and planets but of people and organic lifeforms in their trillioms, who are sentient and, of coruse, selfish, greedy and prone to bouts of evil. Civilisation must exist to run them, and Politics must exist to run civilisation. The Jedi, then, are an order dedicated to using their gifts with the Force to bring Balance, in the form of peace and justice, to the Galactic Republic. George Lucas sees this as the basic definition of 'good'. The important thing is that Jedi see this as a responsibility, but not a right. They don't assume power, they have it given to them; they don't see having the Force as making them morally superior for that reason alone (though they might, with good reason, see their accumulated lives of wisdom and experience as doing that).
The Dark Side believes in the accumulation of power- that is its fundamental joint purpose, it then differs in as to why you got that power and what you then do with it, but it is all based around the selfish desire for more, and the power of yourself and your emotions to make that possible. It is very very attractive- certainly in a Universe without a God who is going to punish you for anything- but George has created a setting- not entirely without foundation - that such selfish evil is innately parasitic. Where the Light Side is self-balancing, the Dark Side is self-destructive, and so it can never really last.
Our theoretical Sirckarans ignore the question of morality- they believe in the Cycle of Life- what Ascar called 'Telebiogenesis'- the continual rebirth of one form into another, based on some form of karmic cycle. It's not just the Light and Dark Side Ascar dosn't believe in, it is also Life and Death he disavows. As you see apparently undeniable proof of life and death around you all the time, it must be assumed that he is talking about something more fundamental than first impressions- so he opes not deny there is a distinction between 'Light Side' and 'Dark Side' force users, he thinks you have just missed the point and drawn an artificial barrier between two things which really come down to the same thing.
Now, what do the three think of the others?
The Light Side think the Dark Side is inherently self-destructive but, sadly, takes out a hell of a lot with it. Therefore, where it is practical to do so, it must be opposed, else it will destroy both individual people, and possibly entire politcal systems. As the Jedi way invovles the wirlding of power they have an entire culture built around making sure the lure of power does not bring anyone to the Dark Side- a constant threat.
(In game, the Jedi have stopped hunting Dark Siders, specifically Kuylen and co, on the idea that it was causing more harm to hunt him than it was to let it run- at which point, what was the reason to hunt him? None- hence Palpatine having to create the Bureau, which doesn't care about how much damage it does
Part of that, of course, was based on them knowing that Kuylen could neevr ultimately cause that much trouble. Unlike the Sith, who COULD take over the Galaxy, hence the Jedi are far more interested in hunting them reagrdless of cost)
The Sirckarans present them with a problem. Can you practice a philosophy of Balance, yet divorce yourself form the moral implications of that? That seems to be what Ascar has done, yet GL says balance = good therefore good= balance, so how can Ascar follow Balance yet not be apparently morally altrusitic? Tricky- he's not actively evil, to be sure (at least has shown no evidence of being so), but he is hardly selfless. Something has to give- is he being deceptive, or is he actually not balanced?
For the Dark Side, the Light Side is simply weak self denial. They have no innate reason to oppose it other than a. it opposes them and b. they oppose EVERYONE, themselves included. As the Light Side is one of the few things that can stop it, we have this Galactic culture of Light vs. Dark, seen in micro scale on Zeiton.
The Dark Side cannot work out the Sirckarans for the life of them- what is the POINT? Why accumulate personal power if you don't do anything with it? Why want to accumulate personal power if you deliberately hold back your own potential? Nutjobs.
For the Sirckarans, the Jedi are fair enough in wanting to bring Balance and do good stuff- but it is a toal waste because in the grand view of life as a whole it is meaningless; you can't make much difference in one existence anyway, life is life, get used to it.
Similarly, they think the Dark Side is fair enough in wanting to accumulate personal power, conquer the Galaxy and make use of their own emotions to gain frightening prowess. But again, so temporal! Not only meaningless in a grand scale, but impossible to enjoy on a personal one because you are either being killed by your underlings, or terrified OF being killed by them. In fact, the Sirckarans probably think the only thing the Dark Side does well is try to get to power- once they have it, they fall apart.
So the Light oppose only as a necessity of their moral journey. The Dark oppose everyone, and the Sirckarans don't think it is worth opposing anyone at all.
So, are they good guys or not? If you asked Master Yoda- assuming you can understand him- he would probably answer, after translation, thusly.
There is one piece of common ground all agree on and that is that the Force exists. People differ as to its true nature. This Galaxy has a perspective of that rooted in the fundamental distinction of Light and Dark. Maybe that is because much of Galactic history has been observing that difference, as Jedi battled Sith- hard to ignore that when shoved in your face, and when the Jedi practice a philosophy which involves temptation from the Dark all the time.
But the Sirckarans, who basically do nothing, face no such temptation (and so as far as the Jedi are concerned, are damn selfish as they aren't helping anyone). Therefore consideration of this has been less important to them. Instead they have formed this view of the Force as an Endless Circle encompassing all things and superior to concepts such as Light/DarkDeath/Life. In that the Force is above all things, this does not necessarily seem to be wrong as such. Ascar thinks you are just at different points on this circle and that ultimate consideration of your 'side' is irrelevant.
Yoda would tell you that from his point of view he is correct- ultimately, under the Force, how you practice your powers is not ultimately changing the nature of the Force. But from our point of view, it IS fundamentally important to how you affect the Galaxy and meet your destiny. You are both looking at the same thing, but from different angles. Ascar might say that his view is superior to yours and that your should be junked but then he's a selfish bugger and would say that; Yoda would say there is wisdom to be found in encompassing the logic of where both views derive from.
As for Ascar himself, he does not create imbalance. He practices a calm and peaceful philosophy that is not detrimental in of itself. Yet his personal attitudes can be dangerous, especially when amplified with the Force, and he was eventually arrested, after all. Not as dangerous as a Dark Sider, and Yoda probably thinks there are Renegades who might do more harm than him.
There!