If it was an popularity contest, then Hal Jordan would win Top Hand. Let's ignore their popularity and analyze the fight. Hal Jordan has the powers of the green ring that everyone knows.
Z'reg .... owns the "freedom's ring". It was carved in a cosmic cube burst. The ring offers omnipotence to its wearer, but only within a radius of 15 feet around it. Properly used is a colossal power. Z'reg is an experienced Skrull soldier and like all Skrulls, he is a shapeshifter.
Disagree. Thundra is strong enough to stand up to the Thing and even to Hulk. Maxima is not able to face Doomsady who is more or less equal to Hulk. Except that Thundra uses her brain more than her pride.