I am against what is happening in the realm. Innocent people like the Thief (who wasn't guilty of being a Stormcloak), or myself (whose name was not even on thier list) being sentenced to death. Since this happens under Tulius's (Empire's) rule I can't side with Tulius. The Thalmor have outlawed the workship of Talos (whose blessing can be received just like those of the any other divines in the game), which clearly marks as Talos as a valid god, so I can't be expected to side with Thalmor either. I take side with the truth.
Ulfric offers people freedom to workship Talos and probably will make amends of ensuring no miscarriage of justice , so I side with him. He challenged the current High King in fair one-on-one combat and won.
Poor Roggvir was put to death for doing what he considered to be right and traditional. So yeah I side with Ulfric , because his cause is Just.
The imperials will further support a scum like Maven Black Briar as their Jarl of Riften, that strengthens my belief that Ulfric is right.
Long Live the Rebel Alliance.
Where to begin...
1) You illegally crossed the border into Skyrim during times of war, They didn't take any chances.
2) The Empire does not willing support the Thalmor nor did they enforce the outlaw of Talos worship until the Thalmor came to Skyrim.
3) The higher ups in the Empire know they will be going to war with the Thalmor again in the near future. They wouldn't be preparing for it if they just did what the Thalmor tell them. NO ONE LIKES THE THALMOR
4) Titus Mede II had no choice to sign the Thalmors treaty, it was either sign it or be destroyed. He made the choice which allowed him to reman and rearm (mistake on the part of the Thalmor for not destroying the Empire)
5) Ulfric is only out for Ulfric and is only using the war and misguiding propaganda to gain public approval and ultimately the throne. Ulfric can rot in Oblivion. He will betray any terms as long as it makes him personally more pwerful (The way of the Voice is a perfect ex)
6) If Ulfric is killed before going to Sovngarde he can be seen there. When you speak with him he talks about how he regrets the war and how it only weakened man.
7) Ulfric is a racist pig. He hates all Mer and Beast races and barely tolerates non-Nord men.
Ulfric Stormcloak is trash, the Stormcloaks are trash, Stormcloak supporters are trash. The entire Stromcloak army will be crushed under the steel boot of the Empire. Then those Thalmor dogs are next... long live the Empire.
Roggvir is your only point.. he didn't deserve his death.