I need learn simplified or traditional characters in Chinese?

If you got interested in the language, understand the history and culture, and perhaps read the classics, the study of traditional characters.
In this way, you can read all the books the way back to the days of Confucius, although changes of grammar as you go. The characters traditionally used among Taiwan, HK and abroad.

Simplified characters are for people interested in modern China, the rise of China and the political and economic consequences. All publications are in mainland China focusing on simplified characters, and there are far more than anywhere else in the world speak Chinese.

If you can recognize traditional characters, you do not understand the effort much easier. Just knowing more easily if not understood as a first language, you do not understand the situation, many traditional characters. They simplify only a few thousand characters, but very often or very complex, so it is difficult to guess its original form.