If I have time to fool around computer model, I tend to trust the spring model better, because it provides more information, such as foundation settlement and deformation of structures, from which, I can exert certain control by detailing techniques.
The pin model, by neglecting the relative movement, in my opinion, is less accurate. However, it has been done over the years by manys, including me. But in order to ensure integrity/longitivity of the foundation system, understanding on behavior of the soil-structural interface, and sound engineering judgement are indispensable.
If you have time to play both, be conservative (but not overly), envelop the maximum if possible. Otherwise, select one method based on the nature of the project, budget and any other constraints, then be consistant throughtout. Your slab will survive if all load case are considered and applied properly. Also important is specify the subgrade preparation properly.