I prefer the look of the negative display version so that is the one I would choose. Negative displays are less practical than positive ones but me personally am not too bothered by that. The negative display on the GD-350 is amongst the best negative displays Casio has to offer.
You mean when you need to go to the toilet at night and you don't want to wake up your wife?well the GD350 was designed for those "special dark, secret missions that demand something extra." ( GD-350-1B - Watches - CASIO )
so yeah, best to go with Neg display, looks cooler- more stealthy and it reduces the chances of you getting caught when on those dark secret missions. lol