I would advise to stick to the "Big 2" (Ctrip and Elong). I have been using Ctrip for almost 3 years and am quite satisfied with their services e.g. in case you have to change a booking short-term. They improved a lot and are now setting the standards in China.

There are lot of copy cats in the market but at the end I think only Ctrip and Elong will survive. Ctrip just won an infringement law suit against qunar.com...