eh if debated properly (people arent dickbags to each other, tall order for this forum I admit) that shitfest could be avoided given that the differences and similarities between them are fairly interesting.
on topic:
If the point of the topic is to compare by parallel well this is the point that is starkly important to me. Who's war was honest. not justified. but honest. Unlike the players the npcs do not have access to both sides of the story. Just their own specific versions and its relative depth. So justification is already out the window as they never had that option. So how honest are they being when they conduct their war.
Honest in what sense?
Garrosh:
Well Garrosh sincerely believed that his people (orcs) deserved better than to eek out a living in the desert. One could say that he should have simply "asked" the night elves for wood. There are two junctions to that point though. 1. Up until the wrath gate incident the night elves were infact giving the orcs lumber, but after the forsaken blight attack (can be debated both ways on what putress actually was, given that in the end one of his goals was to replace sylvanas as leader of the forsaken - manipulated by varimathras). 2. Given warsong gulch and Azshara being sacred to nightelves, whatever they gave the orcs was never really enough probably, and honestly Garrosh isnt the kind of guy whod be ok knowing that out of your 10 bucks you only gave him 2 bucks.
Where Garrosh failed was not the honesty of his war but how his conduct changed (racism, void attunement, dishonorable conduct - total about face from stonetalon) and thus lead to a betrayal/rebellion propogated by that conduct and stoked by the people of the horde (not just orcs) losing touch on that.
Sylvanas:
Sylvanas does twist facts. there is no other way about it. Because in the end her goal is still to commit genocide against humans. Garrosh would have ended in that same place most probably but he would have had the whole horde with him as his purpose was clear, to have Azeroth for the people of the horde (Mind you as an aside we already know this would have lost us Azeroth, as proven by the blank scroll scenario in MoP. The horde alone would have fallen to Nzoth and azeroth would be consumed).
Sylvanas' end goal is in fact to raise stormwind. And her goals are not open to the horde or its leaders. You can see examples of that in the datamined dialogue:
Forsaken assassins in darkshore say "The horde will always be hers" when killed.
Her "do something to Zekhan" once she learns of what he is upto. Yea sure he betrayed her. But the answer isnt some evil moustache twirling gameplan like with koltira.
In the end. She simply plays Saurfang. That doesnt mean Saurfang is stupid. Just that Sylvanas is smarter than him. She is more adept at what to say and what to make it look like. Im more than sure she knew that Saurfang wouldnt agree with blight, raising dark rangers etc etc. She did it anyway and dealt with those "speed breakers" as they came along.
Particularly interesting is the line from a Good War:
And that was almost certainly true, wasn’t it? Elune had intervened. Perhaps she had even stayed Saurfang’s killing blow. And she wouldn’t be the only force beyond the Alliance to oppose Sylvanas’s true objective. Page 82.
which makes you wonder. shes already on an objective. so whats this "true objective" if not the war for the horde?
They might be both blood thirsty instigators. But Garrosh was more honest in his conquest and honestly far more aligned to the horde's interest than Sylvanas or even Saurfang. Which is why I assume that in other timelines he was the greatest warchief the horde ever had.