Good choice original poster, congrats. I'll jump in here post decision since I actually have C10s Cedar & Spruce. I've had the Cedar about 15 months & the Spruce less than two months. If you're like anybody else, you'll eventually probably say, "Hmmm Cedar, wonder what Spruce sounds like?" and vice versa etc etc.
I really just wanted to add that I think the quoted post below pretty much nails it for me. I'd been wanting to post about cedar/spruce even though I know it's been done to death & I would say no two guitars are alike even factory made, so there's other factors that come in to play but if "sweeping generalizations"(I borrowed) can be made, these points below are close for me. For me & my two guitars, the cedar does sound more open and perhaps more forgiving & the tone is perhaps a little more blended, whatever that means. For whatever reason, for now I feel like I'm pay more attention to my technique on the Spruce, it's a little tighter sounding & this guitar is a little bit 'harder' to play but I'm really enjoying the clarity & separation of the voices. Not better or worse, just different. Again congrats!
One thing I would say, when you get the guitar…if & I only say if it's a little hard to play(not saying it will be!) try a set of Normal Tension strings like EJ45s or whatever, you'll lose some volume and some boldness but what you lose in that is made up for in ease of playability, an argument for another day. Enjoy!
The C10 tends to already be a warmer/bass heavy guitar, so I think the Spruce balances that out while cedar may have trebles that struggle more to keep up with the basses. I've tried several spruce C10's and they had that good balance of warmth and clarity. Regardless, I think you'd be happy with either one. When I was first starting out in classical guitar, my assumption was that Spruce = Clear/Cold and Cedar = Round/Warm, but it gets more complex than this. What sets Spruce apart and what makes it the preferred top wood for many of the old builders is that not only does it have better separation of voices, but it has a wider tonal palette or more color and character to the sound. For this reason I gravitate toward Spruce, though I first used to belong to the cedar camp. In the end I'd say neither is better, and it boils down to personal preference. In summary:
->Spruce basses tend to have a powerful focus and firmness. Spruce trebles are clear and more sustaining, while being more colorful/complex. The extra clarity could require more precise technique.
->Cedar basses tend to be deeper, but looser and less articulate. Trebles are rounder/warmer that focus more on the fundamental with less color. Cedar might sound fuller and more open out of the gate. The warmth can help to cover up flaws and mistakes.
Now these are generalities. I believe the design of the guitar has a far greater influence on the sound than the species of wood used. The C10, whether spruce or cedar tends to be a warm guitar right out of the gate and the differences are actually very subtle. If you have trouble choosing, you may be able to find a place that can ship both to you, in which you can simply keep the one you like more.