body is coated with a flexible rock-like shell that is impervious to extremes of heat and cold and can withstand pressure up to 100 Earth atmospheres
Can lift 75 tons (doesn't have to endow himself with this)
Can psionically manipulate rock and earth (including planetary masses 100 miles in diameter and moving a swarm of meteors 100 miles away.)
Ability to affect tectonic plates (causing earthquakes and making chasms)
travel at 75% the speed of light
Has a cosmic axe that emanates waves of destructive force powerful enough to tear Galactus's ship and project highly impervious force shields.
WONDER WOMAN
Wonder Woman is very skilled, has vast strength, speed and durability, a magic lasso, and has taken gods and other mythical characters.
This would be a cool fight. As much as I love Wonder Woman and her kicking ass, I have to give this fight to Terrax. Although WW would put up one hell of a fight. Hell, WW might take this.
Terrax should win, given his cosmic powers. But like Draco mentioned, he hasn't exactly been written like a cosmic stud a good deal of the time. We should assume "peak" writing though, so I'll stay with Terrax.
Last time I saw Terrax kick the entire FF's ass until Surfer came down and kicked his ass. But that was in Fantastic Four #11 and after the heroes were in another universe because they were "supposedly killed" by Onslaught. So that may not count.
I believe WW is stronger and faster but Terrax's cosmic powers may be too much fro her. She's going to have a rough time deflecting giant size pieces of rock thrown at her.
Terrax is Class 75 without enhancing his strenght, but if he tap into the Cosmic Power, enhancing his strenght to Class 100 and enhancing also his physical abilities, throw stones, pieces of granite and other things from all directions to WW, meanwhile blasting her with the axe (he can also blast her without the axe), he can beat her, he's more versatile.