What is the best setup and lure for fishing bass in deep water?

That all depends on what you mean by deep and what structure you are fishing.  I fish a lot of stuff with the boat setting in 50 fow.  I use a 3/4 oz jig with a craw trailer for this deep.   If I am fishing open water or humps I tend to go with a 1/2 oz jigging spoon.  If you mean 15' for deep any jig or tube will do.

I fish the jig till my fingers fall off  ;D ...but today the place i normally fish seems like they caught on to my lure...i switched to a BPS tube bait and started slaying them again.I'm gonna start fishing tubes more now.

Hmmmm... Drop shot...??? :

I'm just like grimlin, I live and die by the jig. My favorite for deepwater fishing is a 1/2oz Jewel Heavy cover finesse jig, I put a baby brush hog on it as a trailer and drag ti and hop it around any deep structure I can find.

I also do a lot of dropshotting, especially in the colder months. I use 8lb fluoro and a small roboworm or BPS handpour DS worm.

Depth is a relative term depending upon where you are fishing, in La Sauceda 12 -15 ft is deep, in La Laborcita, Otates or Zimapán you can hardly say that same 12-15 ft is "deep".

Soft plastics:

Micro Munch Tackle El Gordo tube

GYCB Kut-Tail

GYCB Laminated Lizard

Jig & pig

Hard baits:

DD22

Ledgebuster 3/4 oz Single Willow Blade spinnerbait

The deepest lakes around me are not more than 25 feet deep.  I've been throwing 1/4 ounce jigs and tubes right along side the standing timber and just let it fall on its own.  I've been using 1/4 ounce weights for the tubes also.  If the bait has been falling too fast or too slow the bass will not hit it.

CRANKBAIT, RAT-L-TRAP, CAROLINA RIG.

Texas Rig, Jig, Carolina Rig, or Drop Shot  

Most of the time for deeper water, the bass are suspended (in the thermocline or munching on baitfish). I would suggest a jigging spoon, drop shot rig, c-rig, t-rig, deep diving crankbaits or jerkbaits, or any other method to get you in the 'strike zone'!

Good luck!  8-)

DD22's and a heavy jigs have been the best for me.