I have two model 3s, one with white, the other black. People say the white are more cushy, but they appear identical as far as comfort to me, might just be in people’s head. I will say, I’ve had to clean the white more than the black. I’m sure they are the same level of dirtiness, but things do show more on the white.
If I had to pick, I’d probably prefer the black. The white pops more, but I like the black with carbon fiber additions. I also think the black interior is integrated better, whereas the white seems kind of slapped on, especially with having a black arm rest and things like that.
Heat regarding the seats hasn’t been a factor for me.