A few things to keep in mind:
Filco: It's actually beige, not pure white. But it's also the highest quality one amongst that bunch. Personally I own one and like it just beware of color matching later when buying custom keycaps.
Leopold: They have the tendency to use spacebar with weird stem location that doesn't match most common sets. Some custom sets have extra stems so it's fine, but sometimes you'll run into spacebars that doesn't fit.
Keycool/Noppoo: No experience with these, no clue.