The only thing I've used consistently in every rotation has been UWorld for Step 2. This is a true gem and I have no regrets whatsoever about springing for a 1 year subscription.
Otherwise, the best material really changes from clerkship to clerkship. You'll want to use surgery specific materials to study for surgery, medicine specific for medicine, psych specific for psych. The broad USMLE Step 2 review books just don't give you the depth you'll need for the shelf you're prepping for and aren't a good use of time, IMO.
For more details on the specific resources for specific shelf exams, check out the various shelf exam threads. They're pretty helpful in terms of figuring out which resource to use for which clerkship/shelf.