AC3 5.1-ch English is really the only one you need. The second one is just 2-channel audio and the third one is more than likely some kind of commentary track. If you choose AC3 5.1-ch English, it will have very good surround sound when listened to through a surround sound system. If you don't have a surround sound system, it will be downmixed to 2-channel to play on your TV. Yeah, I would go with AC3 5.1-ch English. That's what I always choose.
Keep the 5.1 and get rid of the rest, even if you do not have home theatre your player will Demux to 2 channel. If you have a disk with Directors Comments they will always be in the 2 channel and you do not want these playing through your movie.
