I was thinking about my new Orc character and decided to let the community decide who he should join. Read his backstory hear (name is Giznar):
http://www.gamesas.com/topic/1372420-skyrim-backstories/

Essentially his dad was a legion veteran but grew to hate the empire because of the white-gold concordant. Should Giznar choose the Stormcloaks who Giznar respects and helped escape from Helgen, or should he take a respectable position in the Legion?

I was always a fan of the stormcloaks myself until I tried Imperial and well... now most of my new characters end up going imperial. It might have something to do with Ulfric's axe named "Coward" but thats just how I started seeing him.

But I guess it comes down to your character and how you see him and want to develope his story.

The background I usually come up with my characters is tragic. It explains why they were crossing the border. usually seeking a peaceful life from the one they left behind. My latest orc was enjoying a freshly caught fish when the stormcloaks and imperials spilled into her camp. In the scuffle she may have pulled a blade and attacked both. She was quickly caught however and thought she was going to die a cowards death on the block. It became clear to her upon getting her freedom back that it was all a miss understanding. She was at the wrong place at the wrong time. Due to her violent background and the search for a more peaceful life, she sided with the imperials. There was "peace" in skyrim until Ulfric killed the high king. My orc believes that there should be freedom to worship any god, and that Ulfric rebelling over just one, a human one at that was simply an excuse for war.

So it comes down to how you view your character's ideals...

Very nice story OP.
But isn't the Orc mother kindda overly protective? I always thought Orcs have a very "hands-off" approach to raising their kids
and if their kid dies, then so be it, he ain't fit enough to live in this dog-eat-dog world.

That said, its really how Giznar himself feels. He might agree strongly about his father's thoughts about the Empire being selfish,
but i think its a choice that he himself needs to find out in his adventures.

That is one of the reason why he would wanna go adventure anyway, to discover the world not through the advices of others, but through his own eyes.

Indeed, it is something that must be seen up against the character himself. The only thing that can be added is that, as you know, the orcs as a whole are more friendly to the Legion where they can use their talents for combat and smithing.

Depending on the exact date when Orsinium was crushed again by High Rock and Hammerfell, Your Orc would have a very legitimate reason to join the Stormcloaks, The current Empire and Emporer allowed it to happen. There is a reason there are many Orsimer Strongholds in Skyrim.

He appears to be an honorable Orc, so I'd lean towards joining the Empire. It would be his family's tradition, and with his career choice of Blacksmith he seems like he believes in following traditions.

His father's disillusionment with the Empire came late in his career, and maybe it's time for Giznar to take up with the Empire to put things right and help restore his father's faith, and justify all the years his father spent with the Legion.

If he actively fights soldiers of the Empire, he is potentially killing men and woman who are what his father was once.