We will try to outline the proper conditions and methods for using each of them.
The spinnerbait is perhaps the number one lure for Largemouth Bass. It is a lure that is quite versatile and able to be used in many different conditions with many different presentations.
Spinnerbaits come in two main styles. The Willow Leaf Spinnerbait has a blade that is shaped like a willow leaf. The large amount of area for the sunlight to reflect off makes this bait designed for visual attraction. It is best used in conditions where you have available light to use to your advantage. It also works best in clear water where the visual range of a fish is at its longest.
Indiana style spinnerbaits employ a blade that is both circular and is cupped at the edges. This bait is designed to provide attraction though sound. It is used successfully in murky water and especially late at night when the available sunlight is either low or non existent.
The presentation you use when casting a spinnerbait can vary based on conditions. This lure is somewhat weedless and can be used most effectively through moderate to light weed cover. I like to use spinnerbaits in lily pads.
I vary my retrieve, sometimes allowing the bait to cruise between the pads at various different depths between the surfaces of the water and two to three feet below the surface. If this method does not work I will try a stop and go retrieve that causes the bait to occasionally drop in pockets of the pads.
Often you will notice the strike occurs as the bait begins its drop. You must be cognizant of this fact and be ready to set your hook.
Crankbaits are designed for catching active Largemouth Bass in deeper water. Visually they appear more like a fish than any other bait you will use. The first key consideration is selecting which crankbait to use. There are two factors to lead to the answer of this question:
1) You should try to match the shape and color of the bait to the forage fish of the Largemouth Bass you are angling for. In lakes where shad are the preferred forage species a round silvery crankbait is in order. In rivers where the forage is generally much smaller minnows you would change to a different color and smaller sized bait.
2) The running depth of crankbaits vary, you must choose the right one for the area you are fishing. Ideally a crankbait will have a running depth very close to the bottom. You will in fact like the bait to occasionally hit the bottom. By vary the speed of your retrieve and angle of the rod you can alter this factor somewhat. The primary running depth however is influenced most by the design of the bait itself. The key determining factor is the clear plastic lip near the eye hole. The size and angle of this lip determines how deep the bait runs when it is retrieved.