In my eyes, Bill and Adam aren't the strongest but they are consistent, each team has a weak link (Sentry, Superman, Gladiator, BB) with intrinsic weakness except this one. They also hold back the least, and they can hang with the big boys of each team enough to get help from the others.
All characters are fighting in character and without any specific knowledge of their opponents before the battle...that's as far as I will say on the matter.
Thor and Gladiator
Advantages: Thor's Versatile powerset, Gladiator's Speed. Both have high tier strength, Thor's energy manip and block, Thor's hammer hits harder than anyone on the field can punch.
Disadvantages:Thor is a non flyer, Thor is not fast, Gladiator's confidence
vs
Black Adam and Beta Ray Bill
Advantages: high tier strength, magic amped attacks, high durability
Disavantages: BA cannot keep his speed up for prolongued fights, BRB doesn't use his hammer nearly as effectively as Thor
vs
Silver Surfer and Sentry
Advantages: Silver surfer
Disavantages: Sentry
vs
Green Lantern (Hal) and Black Bolt
Advantages: Most versatile Team on the field, BB's voice, Hal's will power
Disadvantages: neither are true speedsters, Hal is still a human being with human reactions and durability once you get past the shields. BB isn't quite as high on the strength food chain as the others.
Winners
Superman and Wonder Woman. They can effectively blitz at least one person on every other team.
Close 2nd, BA and BRB. No exploitable weaknesses
Third, Hal and BB
4th. Sentry and Surfer. Surfer might as well be fighting by himself.
People who are giving Supes/Diana team the win are forgetting that not only every team packs a weakness against Supes (magic or kryptonite/red sun radiation), but also the best team of all pack two nasty magic damage dealers (BRB and BA).