For a more realistic fight, likely Robocop: The terminators looked to have very little armor, lots of exposed machinery, and (aside for the Arnold bot) couldnt hit a running human for shit. Robocop is armored, with little exposed machinery. However that pistol he carries is pretty shitty but he is capable of precision shooting.
For actual movies, the Robocop movies were pretty shitty. Terminator movies 1,2, and 4 were watchable so Terminator wins.