The first chinese lunar rover mission is most certainly have a engineering driven mission profile rather than a science driven mission profile. They are there to validate their technology. Any science that can be produced is a bonus, not a overriding consideration. Therefore it should suit them to pick the most tested techniques, preferrably directly based what they have already demonstrated aptitude for.
Ramp system is by far the most tested rover placement and deployment system. It is also the only rover deployment system that has more than one real life success under its belt.
Given Chinese experience with the touchdown cushion rockets on the crew return capsule of the Shenzhou, they are probably confident they can make a rocket cushioned soft touchdown work on the moon. Other deployment mechanisms, like sky crane, is higher risk and involve technology dissimilar to what the Chinese have already experienced with.
godspeed chang er3