About cantonese speaking group in Malaysia, beside KL and Ipoh I think u guys forgot to mention about Sandakan at Sabah. Sandakan people speaks good and standard Cantonese hence dubbed as Little Hong Kong.

I think someone mention in the earlier reply about why Hakka and Hokkien people in KL speak cantonese more over their own dialect. I think i can answer your question as a KL guy from a Hakka family. Its not that we are not proud of our own dialect, in fact alot of us speak Hakka dialect at home and outside if necessary. We speak more cantonese because its the way of life in KL, everyone speaks cantonese so it comes naturally. For example when you buy chicken rice from your nearby coffee shop, you will say "lou sai, cha siu kai tapao".

You will probably ask why Cantonese is chosen over other dialects. This is because dated back to the time when our ancestors came to the then Malaya from China, they landed on the Klang River where the development of KL starts and this group of Chinese mostly came from Guangdong Province with a small numbers from Fujian. Do you know what Hakka means? It means Guest Family because Hakka people actually migrated from the North to Guangdong and Fujian in China. The Hakka people in KL are mostly from the Guangdong Province. I guess now you know why Cantonese is widely spoken among the Hakka people. FYI, Yap Ah Loy the founder of KL is also a Hakka from Guangdong Province.

But the trend now is changing and more younger generation kids in KL speaks Mandarin due to China economic rise and people see Mandarin as a key skill in the future. I dont think there were any Mandarin speaking Chinese migrated to Malaysia in the olden day. Mandarin is a spoken language of Beijing and most Malaysian Chinese you see in Malaysia today is from Southern China.