1. Onoki

2. Tsunade

3. Ay

4. Gaara

5. Mei

One thing for certain Ohnoki is the strongest and Mei is the Weakest

#1 Ohnoki

#2 Tsunade

#3 Ay

#4 Gaara

#5 Mei

I did have a hard time placing Gaara and Tsunade; because Gaara defeated Rasa and Gengetsu on his own basically, and was also the only Kage to briefly contain Madara 3 times, but Tsunade overall has better strength and durability feats against Madara himself, who is much stronger than the Kage Gaara fought, same thing with Ay. Even though Gaara might be second to last here, he's definitely much stronger than Mei by a long shot.

If Gaara's sand touches liquid, wouldn’t it turn wet and solidify? So couldn’t Mei just overpower it using either her steam, lava or water style?

@Posterboi Gaara's sand is durable enough to handle Amaterasu, which is said to be "the pinnacle of fire style jutsu". I think his sand should be able to take it. Also the only reason Gaara's sand was affected by 2nd Mizukage Gengetsu's Hydrification Technique was because it contained not only water, but oil. His sand has never been shown from what I know to break down just because of water. Then again, that does still leave the question of the acidic mist that managed to melt Susanoo, but since it's visible to Gaara and his sand moves at high speeds he should be able to use Desert Suspension to rise above it and attack her from above.

One of the only times I agree with a list.