Should I learn Mandarin or Cantonese?
Mandarin is a unified Chinese language, much developed when China became more open to visitors and especially to business clients, in the 1920's to avoid the problems associated with so many different dialects being spoken. When the Communist Party took over in 1949 China became inaccessible again, but as you know things have now changed yet again. Cantonese and other dialects are discouraged now by the Chinese government and in Shanghai there are huge placards telling people that they sound like country yokels when they use the local Cantonese dialect. Proper-speaking people speak Mandarin. The Shanghai folks don't take much notice of that, and neither do the people of Hong Kong, though many of those do speak Mandarin as well as Cantonese.. Most Chinese people abroad, and especially in USA and Europe, are from Cantonese-speaking areas and continue to use it as their first language.
Is it easier to learn Mandarin or Cantonese first?
Mandarin and Yue (Cantonese) are different, although closely related, languages, so learning one and then the other is like learning French and then Spanish. The difference is that Mandarin and Yue share a writing system. Mandarin is probably easier since it has only four tones. Yue has eight tones (with some dialects having as many as ten). Yue has also preserved more of the Middle Chinese sound system (including about a dozen more syllable-final consonants). I can't speak for the grammar, but the sound system of Yue is more difficult for an English speaker to learn than the sound system of Mandarin.
Is Mandarin Harder Than cantonese?
Mandarin, since itis the basic form of chinese which has only four tones as you see, mandarin is the most use language around the world