^ HAHAHAHA. You honestly think Chimchar is the best? ROFLWAFFLES!
But seriously, it depends on what role you want it to fill. Infernape is obviously the best sweeper, physical, special or mixed, so if you need a fast poke to do some speedy cleanup, take Chimchar.
If however, you are looking for more of a tank, Torterra is the way to go. His speed is awful, so you won't be doing a ton of sweeping. However, his attack and defense stats are great. This is what makes him such a great tank. If you want a poke that can take some heavy damage, and then turn around and deal massive damage with awesome STABs, go with Turtwig.
Empoleon is the last choice, and is sort of a toss-up. He makes a good special wall, but an even better special and or physical sweeper. He can dish out massive hurt with his STAB moves, and boost his speed, making him a powerhouse. His defensive side can stall other pokes out, and then do some damage of his own. So if you're looking for a poke that can go either way, pick the penguin.
EDIT: To whoever the hell repped with the *expletive* comment, knock it off. I honestly believe Empoleon to be the best starter. he has more options than the others, and his typing makes for a good all-around pokes.