I think Cantonese being loud is just the speakers' problems... The restaurants here are always so loud because of all the Canto-speakers screaming at each other.

I think Cantonese uses a lot of slang and isn't as "elegant" as Mandarin. You can see this most clearly in contrasting Cantonese with Mandarin songs, I think.

I speak both Cantonese and Mandarin and I know a lot of Korean and Japanese speakers. If I had to pick one to be the most elegant sounding I think I would pick Mandarin, and Cantonese as the strongest when it comes to phoenetics.

And Cantonese has some of the best curses :)