[ithacaartist]

I'd say the two most important ones are the firing pin spring and the main action spring. These have to be up to the task in order for your pistol to cycle properly. Well, OK, the pistol won't be worth much if the extractor's spring is broken, either. You might hold off on the other ones, which will become obvious when they need replacing. However, a spring rebuilding kit containing one of each is a good idea, and won't set you back all that much.
Springs do break and wuss out, but this way, you can keep shootin' while the reserve's replacement is acquired.