Newest handbook says that he can lift 100 tons. Read them for a while.
And if we want to go by feats in comics, which I do...
#118. Namor soundly defeated the Hulk, by knockout, in a huge underwater collision. Hulk was knocked from Atlantis all the way to the mainland shore where he laid unconscious and then reverted back to Banner. Namor was rocked but never lost consciousness. Off the top of my head these are some of Namor's best feats. In no particular order they are:1)Namor carried a 50 ton anchor, with one arm while flying in the air.
2)Namor lifted a huge portion of an undersea mountain that Orka's whales dropped on him.
3)Lifted an oil tanker that weighed in excess of 110,000 tons.
4)Lifted a sub-marine from the bottom of the sea and placed it safely on shore.
5)Lifted a 2,000 ton destroyer and slammed it into Attuma.
6)Namor can absorb millions of volts of electricity and use it as a weapon by throwing it at his opponents.
6)Namor can see and find invisible objects because he posseses the powers of the blind cave fish that has a radar sense.
7)Survived unharmed, in a fall from space after battling the Stalkers.
8)Namor took a direct head shot from Thor's hammer which only made him madder.
9)Was only minorly stunned when Krang's fision bomb exploded while Namor was holding it. This is equivalent to a small nuke.
10)Namor drilled through miles of sea rock by spinning his body at tremendous speed.
11)Namor has created great tidal waves. In one TTA #100 he wiped out an entire island and the Hulk along with it.
12) While being held by Magneto's power Namor slammed his fists so hard to the ground that the earth quaked for hundred's of miles.
13) Namor, as are all Atlanteas, is totally impervious to the affects of radiation.
These are just a few that come to mind. There are many more. Remember, Namor only uses his natural birthed hybrid strength. He needs no cosmic or gamma rays, no armor, no weapons or hammers. It's just his Atlantean-human blood, muscle, and bone!
A few nights ago on television they put up a virtual battle pitting a Polar Bear against a Walrus. It was unanimous that on land the Polar Bear was more vicious and more powerful than the Walrus. But, the Walrus pulled the Bear into the water, it's own natural element, and killed the bear. It was acknowledged that not only was the Walrus stronger, faster, and more agile in the water but the Bears strength and power was not as affective. Had the Bear kept the Walrus on land the Bear would've killed the Walrus by wearing him down and keeping him out of his element. This the Hulk needs to learn. Hulk has done many more impressive feats than Namor except when they battle in the water, it's Namor's element, and Hulk is second best.
Namor = Class 100. Accept it.
And I admit that Thor wins most battles. He is strong enough to go with Namor until his strenght starts to deplenish, and he also has the experience and skills with him. He wins 7/10.