I'd say Beta Ray Bill.
Why?
Well, because while he was 'normal' (well, as normal as an alien lifeform could be) he faced off against Thor and fought the Norse god, Thor lost his hammer, and Beta took it. Odin had to make StormBreaker for Beta Ray to give back Mjolnir to Thor.
Thus, if I HAD to place a bet I'd place it on Beta Ray Bill (assuming it is the normal Thor we are talking about and not the Odin force Thors or the 'place name here' Thors).
Tossup. They have both, high and low showings that could equate to each other but i'd give Thor the nods on durability. BRB is just too durable while Thor has better range of powers with or without the hammer and the chance of having warrior madness..
i would give slight edge to thor because he is a ful god and can use the godblast if needs be or draw power from asgard itself als0 i think strentgh wise they are equal but i think it would be 3 out of 5 to thor bill is a mean fighter
Odin sent Thor and BRB to a place that will give BRB advantage because he wanted his son Thor to be humbled once again. They are even right down to the "T" but Thor is still more powerful than BRB because Thor is a hybrid god being a son of a sky-father "Odin" and a Elder God "Gaea", stated in Thor Annual #11 to Gaea, I want a son whose power is greater than Asgard itself, Thor has the power of Earth and Asgard and he knows how to use his full potential. And Thor has the ability to warrior madness on BRB like he did before and BRB didn't have a chance in hell of defeating Thor. Thor wins 6 or 7/10 more experince and more raw power.
Thor beats BRB more times than not. Even though they're nearly equal in power and skill, Thor is more experienced and has more determination.
Thor's stood up to beings vastly more powerful than himself, including Galactus and Ego, and prevailed. Bill has the same potential, but isn't quite there yet.