All depends on where you're from (in Malaysia), and which neighbourhood (in Singapore)! For Malaysia, Kuala Lumpur and Ipoh are very Cantonese (the former is what might give you that impression) while Penang is very Hokkein and Cameron Highlands is Hainan. I'm not sure what Chinese dialects prevail in other big cities in Malaysia (there are, apparently, small towns that are predominantly Hakka).

When I was a child in Singapore (been decades for me) certain old neighborhoods in old Singapore (largely gone all redeveloped and inhabitants moved to HDB flats) were reputed to inhabited by speakers of certain dialects. Before people started to mandarinize names, it was very easy to discern a Chinese person's dialectical ancestry by the anglicised spelling of their names. I certainly remember people with Cantonese names though, as you say, Hokkein and TeoChew are more prevalent.