I'm going with T800's seriously seem to be underestimated here, one holds a mini nuke(two technically) my fault for one, two they're way stronger then both Predator and Aliens combined(look to T3 and T4 feats)
Pure lava was poured on one in T4, did nothing...so I'm sure they can manage against the acid.
Humans have killed both Predators and Aliens with far less effort then a Terminator generally speaking. Also, the explosion at the end of T1, that would kill a Predator and/or Alien huge fire blast? yeah...Terminator just got up like "yeah...now what"? lol
Totally going T800's here...if anything it'll come down to Preds vs. T800's ultimately.