This would depend on what exactly you are looking for. Do you want a unit with replaceable modules? Is cost a factor? How often does lightning strike near your home or do surges occur within your home? These questions should all factor into your main decision on what unit would fit your needs. The 52120-CM2 has replacable modules.
The 51120-1 is not module and does not have replaceable modules. Neither does the 42120-1.
All 3 units will work for you as long as you have single phase 120/240V service into your home.
Any of the units you listed should provide proper protection to your home in the case of a surge.