Sol was there, he knows how bad I pwned Judge.
Anyway, onto the fight.
Strength: I'll give it to Kain as Nihilus has never really had to use strength, tho he is very big and stuffs.
Speed: Kain.
Stamina: Nihilus, while doubly weakened, fought the Jedi Exile, Visas, and Canderous, 3 on 1, and for most of the fight WAS WINNING.
Durability: I took away Kain's immortalness so tie I guess.
Skill: Swords, Kain, as unfortunately Nihilus has no feats to back up his saber skill. However, Nihilus was beating three opponents, two using sabers, the other using a blaster or vibroblade, simultaneously. Magic/Force, Nihilus of course.
Power: This is where Nihilus COMPLETELY trounces Kain, he tore his whole fleet from the surface of a planet via TK, he(even while doubly weakened) kept his cracked ship from falling apart, kept a mental hold on those in his main ship and piloting his other ships, and kept all on his ship alive, simultaneously. He has cosmic awareness on a galactic level, able to sense things far across the galaxy, and has many other abilities(lightning, drain life, the works) as well.
Reach: Nihilus is a 6'7" tall sonova b*tch, and wields a lightsaber, him.
Range: Nihilus.
I think Nihilus wins.