A few things from someone who lives in Northern California and loves Colorado. Although, I have never wheeled in Colorado.
Politics of California suck as most know, however you may not have to deal with this much being in the military.
Funny, as crappy as they are. Vehicle restrictions aren't bad here. Heavily modded jeeps every where, no problem.
Plus side you have great mountains and wheeling plus the ocean. I still love having just a 2 hr drive to the coast. And the Northern California coast is beautiful.
Colorado is gorgeous and from what I have seen there is a ton of great wheeling.
Pot is fully legal is Colorado, medicinal only in California. Probably doesn't matter for you. Or at least I hope our military isn't high.
Speaking of drugs, tons of great breweries and wineries in California.
Snowboarding or skiing, both are great.
I'll admit. I love San Francisco. Cool town.
Denver is cool too, but different.
I've traveled quite a bit and Tahoe still blows me away. As does Yosemite.
Colorado has coors. I keep them in business.
California has both the lowest and highest points in the lower 48.
The lowest point, while some might say is Death Valley, is actually the fact that jerry brown is in his 3rd term as governor and will most likely get a 4th.
California has a grizzle on its flag but we killed them all. So less chance of being eaten alive.
Although we do have too many mountain lions since the libs stopped almost all hunting. So now you're back to being eaten alive.
IDK. It's a toss up.