A game of thrones? Books or TV Series?

I'm confused! I do not know what should I do : either buy the books, or watch the tv series. I watched a teaser on youtube and I saw that the type of series it is, i think it is more understandable and enjoyable by watching instead of reading it. But I do not know what I should do. I think watching it explains the series better.. I don't know Is it better to watch it? Or should I buy the books? Thanks!