The bench press is the best overall upper-body strength exercise, but in terms of the best chest BUILDER, it's not the top choice. Many lifters don't feel it in their chest all that much. And do it too much and it'll start to piss off your shoulders.
If you really want to build your chest, add some rings flyes to your workouts. (Gymnastic rings, TRX, or Blast Straps will work for this.) I've never had an exercise fry my chest so badly.
In the video below, I show both ring flyes and ring push-ups with bent-arm flyes in between – which is a great exercise in its own right and is also a great progression to work towards full flyes. If you're able to crank out full flyes, this makes for a hell of a mechanical drop-set that's guaranteed to have your chest hating you the next day.
Ring Flyes, Bent-Arm Flyes, and Push-Ups
Here I'm doing 5 flyes, then "dropping" to 5 bent-arm flyes, then again "dropping" to push-ups. Basically, you start with the toughest variation and progress to the easiest as you fatigue. Add a weight vest if you need to ramp things up.