Absolutely start with the little one, unless you are independently wealthy!
To figure out which motors you need, estimate the needed torque. If you direct actuate, the load is the weight of the object, times the distance between the axis of rotation and the center of mass of the object. If you use something like a linear actuator, you instead get force, so load is simply mass times gravity. You also want to pay attention on the difference between "stall torque" and "continuous torque" -- motors that work at their max (stall) load more than just briefly, will overheat and die.
Once you know which motors/actuators you need, you can pick a RoboClaw that is rated for at least the amount of current drawn by that motor/actuator. For example, if you're using a motor rated at 5A, you can use a 5A rated RoboClaw; if you use a motor rated at 20A, you can use a 25A rated RoboClaw.