In case you’ve just started learning Chinese, “traditional Chinese” refers to the characters used before simplification reforms enacted during the second half of the 20th century in Mainland China. This means that traditional characters are still being used in Taiwan, Hong Kong and in many overseas Chinese communities. Simplified characters are then, as the name implies, simplifications of the traditional characters.
For most people, teaching simplified Chinese characters is the obvious choice, because most Chinese-speaking people in the world use them. People living in Taiwan or Hong Kong naturally learn the traditional character set. So perhaps it really comes down to where you’re born or live.
The two character sets have their own pros and cons.
Traditional:
Provides more visual cues to support reading and helps facilitate learning and character recognition; Researchers have explained how this often helps young children recognize traditional characters more easily than simplified characters. Also, learning traditional characters first can present an easier transition to simplified later on. However, traditional characters can take longer to learn how to write and there are fewer resources in the US and it is sometimes harder to access materials unless you buy/ship from Taiwan/Hong Kong.
Simplified:
Strengthens visual and spatial relationship skills due to the way simplified characters are structured and formed. Simplified characters provide fewer visual cues so they require the student to pay more attention to detail when learning characters via rote memorization. When controlled for reading ability, this method has shown that children learning simplified characters demonstrated superior visual skills. Understanding simplified characters may be more useful as the majority of the entire population of mainland China utilize this form of writing.
Further Reading:
Basic Rules of Stroke Order
Tips on Chinese Writing