The increase of disabled people with leg-muscle problems has elevated the importance of wheelchairs. Most available wheelchairs capable of stepping over obstacles utilize wheels coupled with a double planetary gear structure, a crawler mechanism, or a rocker-bogie structure. Each of these mechanisms has different limitations and benefits. Two types of stair-climbing mechanisms are proposed and compared with a typical stair-climbing system composed of a double planetary gear structure. One is composed of a double planetary gear structure combined with a fixed crawler mechanism, and the other is composed of the same elements and a rotatable crawler. The evaluation of the stability and user comfortability of these systems is based on the amplitude and the weighted acceleration during the climb and descent of stairs. The theoretical trajectories are used to calculate the maximum amplitude and weighted acceleration. Experiments using scaled models are also conducted. The results indicate that both theoretical and experimental approaches proved that the mechanism composed of the rotatable crawler mechanism is the best option among the tested systems. Furthermore, a more stable descending operation is realized by switching to a single planetary gear structure. By considering stairs of different dimensions, the behavior of the mechanisms and the stability of the chosen system could also be assessed. The mechanism chosen in this study can stably transport the user while providing a comfortable experience; therefore, it is expected to improve the quality of life of wheelchair users.