The trend, at least in the USA, is to make the sink height closer to a kitchen counter verses the more typical height used for a bathroom. But, this very much depends on the people that will be using it...if both children and adults, you'd probably not want it that high. In the USA, a standard kitchen counter height is 36" (which I find too low). 32" vanities are fairly common. It really depends on what you want...there is no right or wrong answer here. If you're doing a wall-hung, you have total flexibility, if you're putting it in a cabinet (vanity), then you're 'stuck' with what's available where you live which may be different than what's available in the USA.