I like to use a spinner bait in murky water with allot of weeds, and a crank bait in less murky water around pilings, wood, and rocks. One thing you have to keep in mind about spinner baits, is that they are semi weedless, and crank baits are not weed less at all, although they can be ripped from cabbage and other softer, weeds, you'll have no chance if you use it in pads and reeds.
Spinners also but out more vibes and less sound and cranks but out more sound, and less vides. Spinner baits also put out a bigger image and are better for targeting BIG , wile crank bait can still produce big bass, the little ones can also get 'em good (at lest better in my experience).
You can also fish a spinner bait different ways, on the top slow rolled and jigged, you have no hope jigging a crank bait (with lip).
Spinner bits tend to more effective in low light situations, they will give more flash and vides. Wile a crank bait, with give less flash, and more rattles. But if you add rattles to a spinner bait (some thing I have done when the going gets tough) you can have the sound of a crank bait, and the vides, and flash of a spinner bait!
But if you're trolling, as apposed to casting, you should use a crank bait, if your using a spinner bait, than the blade will get rapped in the line, and if you using mono, the line will eventually snap. :'(
Crank baits can also be better in areas with high current, a spinner bait can also get the blades wrapped in the line if the current is strong
enough.
