Super Robot Taisen OG: The Inspector

High quality animation and kickass soundtrack. Both are manly shows for manly men.  

The opening in the forest 1ep is almost the same , and the story. 

both have loads and loads of characters, and with ludicrous amount of ridiculously awesome action. 

Both shows have loads of characters, factions and politics. Super Robot Wars has far more than Code Geass does though, and does not focus on any single person as much. 

Both are on the extremes of Super-Robot testosterone-inducing ridiculousness. 

Both share some staff and have similar futuristic world-war like scenes. The main difference, of course, is that Super Robot Wars has Super Robots.