I'm a western rider. Always have been, probably always will be. However, I decided to take up riding English a little on the side, because it looks good to have an all around horse and to be an all around rider.
That being said, I can't BELIEVE how much my own Western equitation has improved just by riding English, too. Many Western riders like me develop a nasty chair seat among other bad habits which riding English totally helps. English riding completely helped my balance and alignment in my Western saddle, not to mention my heels
I'm not saying either one is better, but one definitely helps the other. I think EVERY rider at least should know how ride both. You should definitely take lessons in both!