Lobo. In my opinion he's stronger in the h2h department, and it's also likely that, due to Lobo's uber HF, Thor wouldn't be able to cause any lasting damage via fisticuffs.
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"I am tired of Earth. These people.
I am tired of being caught in the tangle of their lives."
Lobo's like a sponge when it comes to absorbing hits.
Even the fight where Dox beat him, he pretty much took zero damage, and just seemed to pass out, which is PIS considering all the beatings he's taken before. Even Despero couldn't put him down with two big punches.