Design wise Empoleon wins. I liked Torterra when he first came out, but all the pictures I see of him make him look fake and plastic. I hated Infernape at first but now he is pretty cool.
If Empoleon didn't have that retarded ground weakness, then he would be my pick for sure...he's just too hard to use with it. Some say he is the ultimate dragon killer, but unless they have choice outrage going, you'll be destroyed by earthquake. That and there are too many fighting types (not even counting electrics). There are just better steels out there (Scizor, Lucario, Magnezone, Bronzong, Metagross) and for Scizor, he looks cooler. There are also better waters (vaporeon..although he has crappy defense, Swampert, Gastrodon). He would be awesome if he had some speed, of course he has agility, but it still wont outpace much.
Torterra, he's nice with a rock polish, but too many things say hi to it.
Infernape..he's too frail for my taste, but he looks cool (hey, better than Blaziken), and there really isn't another fire pokemon that can compete with him (heatran will get destroyed). Although Infernape too is walled way too easily by anything faster, and if he doesn't OHKO, forget about him lasting.