Frame material alone doesn't really tell you enough to say whether a bike will be good for your intended purpose or not. For instance, I own a 1984 Pinarello with a Columbus SL steel frame and a 2008 Surly Long Haul Trucker with a 4130 Chromoly frame. As I understand it the Cyclex steel use in the Columbus SL tubes is very, very close to a standard 4130 alloy in terms of chemical composition. How tubes are constructed and how these two frames are built, on the other hand, is by no means similar. These two bikes don't have a similar ride and neither one would be particularly well suited to the job done by the other.
Something similar could be said about carbon frames except that carbon frame construction has even more degrees of freedom than steel frame construction. High end carbon frames are precisely designed to provide the particular ride characteristics that the designer is after -- light weight, vibration absorption, stiffness, aerodynamics...all of these are possible but none of them are automatic. So when you consider a cheap Chinese carbon frame, what are you getting? Who knows? People seem to like them. Most of them don't seem to be junk. Most likely they are copies of design traits found in other bikes. You just don't know which traits until you ride the bike.
My suspicion is that buying a cheap Chinese carbon frame, as compared to something like a Specialized or Trek frame, is like buying a generic 4130 steel frame compared to a frame made with Reynolds 853 tubing. It's probably not going to suck, but you shouldn't expect to get the ethereal qualities you hear other people raving about.
Aluminum, in spite of all rhetoric to the contrary, can also be a good choice. My favorite commuter is aluminum. A lot of really high quality bikes are being built with aluminum these days. Aluminum is cheap, it's light, and it doesn't rust. With proper care, it can be built into a frame that is strong, responsive and comfortable. I think the reason aluminum gets a bad rap is that it's really easy to build a very crappy frame with aluminum and a lot of them have been made.
What I'm saying is that you need to think a lot about what you want out of your commuter (and I'm sure you have) and then pick a frame that provides the qualities you want.
It sounds like durability is one of your priorities. As other have said, carbon frames aren't particularly fragile. They're amazingly tough. The idea that they're fragile should have gone away when reputable companies started selling carbon mountain bikes. Carbon frames can even be repaired these days. The knock against them is the expense. Cheap Chinese carbon negates that to some extent, but if you manage to damage your cheap Chinese frame you probably aren't going to spend $300 to have it repaired and carbon, when you do manage to damage it, really does need to be repaired. If you get a huge dent in a steel frame, most of the time you can just keep riding it and see what happens. If you get a crack in a carbon frame, that's a really bad idea because the failure mode is much less forgiving.
I've got a carbon Ridley road bike. I never ride it to work because I don't want to expose it to the abuse of commuting. It's not that I think it is likely to be destroyed. I just don't want it to get beat up. I built my 2001 LeMond (Reynolds 853 steel) specifically to ride to work on the days when I feel like riding a spirited road bike. It's every bit as fun to ride as the Ridley, but I can beat the crap out of it and not worry about it. It helps a lot that it was already scratched and dinged when I started. The first scratch is always the most painful.