I do 2-4 for major and 2-3 for minor.
I have tried 2-4 for minor, but I feel like I have to twist my wrist around to get 2 lined up under 4 and my whole hand ends up in a weird position.
I've also tried the 1-3 major, 2-3 minor combo. Personally, I had a couple of problems with this fingering:
First, I think that the more fingers you have down on double stops, the better. They are kind of physically demanding anyway, so having 2 fingers down on the E-string and 2 on the G-string for major 10ths gives a little added strength.
Second, I like the way this fingering sets me up for other useful and related double/triple stops without shifting or changing hand position much. For example, If I am playing a Bb-D (2-4) double stop, I could also play Bb-Db (2-3), Eb-Db(2-3), Eb-D(2-4), Eb-G-Db(2-1-3), Eb-G-D(2-1-4), or Bb-Ab-D(2-3-4) all without moving my hand.