I guess it's better to learn simplified Chinese (Mandarin), which is popular and acceptable almost anywhere as long as there are Chinese speaking people. If you speak traditional Chinese (Cantonese), only people of south (especially in Guangdong province) will understand you, and maybe Chinese living in Singapore and Malaysia could also understand you. But if you speak Mandarin, almost people in Whole China will understand you, and Chinese in Singapore, Malaysia, etc. could also understand Mandarin I guess.