Traditional or Simplified Chinese... which writing should I learn?

You should learn Simplified Chinese as China is using it. Its more simple to learn to read and write. If you want to learn Traditional Chinese, you should also learn Simplified first, as its more difficult to start first and most of the words are the same.

Majority of the Chinese are using the simplified one as its the offical standard of Chinese since the 1980s. Singapore and Malaysia is also using the simplified version, so do rest of the world. But the elderies still prefer the traditional one as they are educated on it, especially in Singapore and Malaysia (more towards in Malaysia).

Hong Kong is still using traditional version as its offical one, but its slowly move towards simplified one, so its gaining popularity now of days. Canton is a part of China Mainland, so simplified is used. Macau is now starting to educating its citizen about simplified version recently although many still read and write traditional. Taiwan is the only place left stubborn to sticked to traditional one and still confusing on using its Zhu-yin rather than Hanyu Pinyin, although Hanyu Pinyin is the offical standard in Taiwan now of days.

In China, Chinese is refer as Pu3tong1hua4 普通话, Hong Kong and Macau called it Guo2yu3 國語(trad.) or 国语 (simplified). In Singapore, Malaysia and recently Taiwan, its called Hua2yu3 华语 or 華語. But overall, all refers to Mandarin Chinese language and its called Han4yu3 汉语 or
漢語. Written as in zhong1wen2 中文.

Hope the above answers your question. Thanks for asking.

I come from China, I love china. We can learn from each other, maybe we have common interests.

MAINLAND CHINA: Mandarin and Simplified Characters
TAIWAN: Mandarin and Traditional Characters
CANTON, HONG KONG AND MACAO: Cantonese and Traditional Characters

If you don't have preference between HK, Macao, Taiwan or Mainland China, I would suggest to start learning
Mandarin Chinese, and so simplified characters. Once you know at least 500 characters and you are used to radicals, you can learn few "rules" to pass from simplified characters to traditional. It's not difficult.

But about speaking, between Cantonese and Mandarin, there is a big difference. You can still understand one or the other while reading, but not listening. Unless you are planning to live in HK, Macao or Canton, I would suggest to study Mandarin.
Keep in mind that where Cantonese is the main language, they also study Mandarin at school, so you will anyway be able to communicate.
I studied Mandarin, and it's not that difficult as expected. Moreover, there is plenty of learning material online, while Cantonese is too specific.

I link as source what are the good points why simplified Chinese is easy to learn, some point may be in common also with Cantonese.

I am a Taiwanese, I think all the people who live in Taiwan or Hong Kong can understand Simplified Chinese Characters. Because it’s a doddle for us to guess simplified Chinese Characters.
But I think when Chinese people visit Taiwan, when they see all the Traditional Chinese Characters, they can’t understand the Characters as easily as we could when we are in Mainland China.
As to which would be better for you to learn, I have no suggestion.
I just think if you have the potential to be sent to China to manage an American company, etc., then, of course, to learn simplified writing is first choice.
And if you really want to learn Chinese quickly, coming to Taiwan or Mainland China would be a short-cut to learn Chinese.

Both