Cockers are not calmer dogs than Springers, they are very similar in some aspects having both show and working types and some having higher work drive than others. It is not unusual to get calm Cockers or Springers (this would depend on their parents temperament amongst other things) but it also not unusual to get extremely wired dogs in both breeds.
Both breeds require a lot of exercise, are full of beans and get bored easily.
I've had a working cocker and she was a lot more energetic (loopy) than my current springer. I've also met show cockers that were as busy as my springer and springers that were busier than my cocker (you see where I'm going with this?).
Think long and hard about the type of dog you want, the time you have, the training you can commit to and as Selina suggests talk to some rescues and see what there is out there. You will find a dog that suits your lifestyle perfectly, whether or not it's a springer, sprocker or other depends on what you decide would fit with you best.
Good luck