I think the C&C vs x-pen debate depends on your individual bunnies. Some rabbits are notorious escape artists, good at jumping/climbing/digging/pushing their way out of anything. A rabbit like that I would not trust to keep in an x-pen 
My two are in a combined setup. 2x5x3 two level C&C for when we can’t supervise (at work and sleeping), and attached x-pen for whenever we’re at home (I’d like to expand their access to the rest of the room, but was waiting for better litter habits, now I just have to bunny proof). Most days they have at least 6 hours with access to the pen, although they seem to spend at least half of that sleeping on their upper level, lol.
Here’s some pics, ignore the toilet paper tubs on top of the x-pen, they’re there because I have the connecting pegs upside down, which means they stick above the height of the fence, the tubes prevent me stabbing myself on them when I step over. 

