I just started on both sites, and they're very different. For me, I've had more success on SM because the emphasis on private shows fits my camming style better-- I use BDSM toys and cater to fetishes, so what appeals to one viewer may turn off the next. I like being able to focus on one or two people and ask if what I'm doing is working for them. Plus my personality is more calm than bubbly, and being constantly moving and trying to do attention-grabbing things for hours would just be exhausting and feel fake. Most of my tokens on CB have come from privates and two or three regular folks, and I haven't had much success getting public shows or ticket shows off the ground. But if you're more high-energy, work well in groups, and have a widely appealing aesthetic, CB might be a good place for you. CB also has lots of apps and bots to experiment with and play games on.
Wrt traffic, some of that will depend on your ranking. CB's algorithm focuses on the number of viewers in your room. On SM, I don't think members can see how many other people are in your room (not 100% sure though), and the placement takes into account the quality of your stream. So if you have a good camera and a fast computer, you're in luck. It's also the opposite of MFC's camscore-- working more hours gets you a higher placement, even if you don't make as much during that time. I really like this; it's motivation to stay on and stick around even when I'm discouraged.
You probably already know this, but just in case, SM doesn't allow below-the-waist nudity in public chat, while CB does. So that limits what you can do, but it also weeds out the freeloaders and most of the demanders. In my experience so far, most people come to SM expecting to spend money (just not necessarily on me, and they'll leave right away if I'm not their type), while a good chunk of people come to CB expecting to get something for free. YMMV, of course.
