Which cave tour is the best?

One cave tour is not better than the other, they are just distinctly different:

• Rushmore Cave is the least strenuous (200-300 steps) and is a 1 hour tour.  Famous for the largest concentration of stalactites and stalagmites found within a cave system in the Black Hills.
• Wind Cave National Park has 500 steps and is 1 hour long.  It is the 4th longest cave in the world and houses the largest concentration of box work in the world. 
• Jewel Cave National Monument is the most strenuous cave tour.  1 hour and 5 minutes long with 700 steps, it is one of the longest caves in the world.  Jewel Cave is famous for its abundance of crystalline structures.
• Black Hills Caverns offers The Crystal Tour, an easy ½ hour, 1500-ft walking tour, in the 1st level of the cave, or The Adventure Tour, a 1-hour tour of all three levels of the cave, approximately 3/4 mile. This is a moderate walking tour.
• Beautiful Wonderland Cave Tours leave approximately every 20 minutes. Courteous guides, schooled in cave geology will guide you at a leisurely pace, share with you the interesting history of the cave, and explain the many different formations along the way. The temperature is always a pleasant 47 degrees, so a light wrap is recommended. You will also want to wear comfortable walking shoes.