The original anime doesn't follow the manga, while Brotherhood follows the manga. I think anda should watch both. The original anime, despite not following the komik jepang completely, is incredibly emotional, though it's also very dark as well. It's amazing in my opinion. Brotherhood is lebih humorous and less dark, but it's great as well! But yeah, in my opinion, anda should watch both. The lebih Full Metal Alchemist the better, right? <3