Both?Actually u should start mandarin first then cantonese if you are not native speaker of cantonese.Written cantonese is hardly taught in Malaysia and usually just follows the standart chinese form.

IMHO Cantonese outside of hong kong is almost exclusively spoken only.Once you master mandarin it shouldn't be too hard learn a bit of written cantonese(which is almost the same as standard chinese with quite a few extra words).

You guys do know that being proficient in Cantonese helps in learning korean and to a certain extent japanese and vietnamese and others?I just found out recently.