I don't replace my sand. When I do vacuum I do it carefully and just hover above the sand to suck up loose detritus. Light colored sand can show dirt easier
I have black sand in all my tanks for now. Tho I have a 3 gal
I may try white sand in, because it is lovely. Darker sand may also encourage fish to color up more. They try to match the bottom. Light sand may wash them out?
You just don't want to go too deep on sand or you can develop pockets of bad bacteria and gas. I haven't had issues with this. I have one tank with gravel, but it will be converted to Sand sometime this year I think.
With a Fish Only tank, esp. with big fish, gravel may be better. But for planted tanks, straight gravel can work, but it's harder to plant in and if the size of the gravel is too large, it won't hold nutrients very well and it may be hard for roots to grow. My gravel tank does grow plants, but they seem to struggle compared to my sand tanks.