Can white grape juice be used for kiddush at night, day or havdallah? If one has been using it because of preference was he not yozei? Whats the best drink that can be used for kiddush at night , day or havdallah lechatchillah? Mevushal. red , etc.
White grape juice can be used (272:4), though some Rishonim write that white wine is not valid for Kiddush (Ramban, Ran).
Therefore, there is a preference for red wine, but if somebody has a preference for white wine/grape juice, it can be used.
[Some suggest adding some drops of red wine to the white wine, to color it red (the white wine should preferably be added to the red, and not the other way). However, this does not necessarily help for the opinions who invalidate white wine.]
Nowadays, almost all wines are mevushal, and these are fine for Kiddush and for Havdalah. According to some poskim there is a preference of wine over grape juice, but somebody who prefers grape juice can comfortably use it.