I think this might deserve a poll.
Moyes for me really didn't have a style. In some games, they would just pumping crosses into the box. Other times, they tried to have intricate passing. So there wasn't a clear definition on how football should be played. I am unfortunately one of those that supported Moyes till the end, and I honestly thought he did well against the weaker opposition. He just wasn't tactically good enough against the big boys. But in terms of being attractive, they were ok to watch (Actually even Sir Alex Ferguson's last few years produced very average football to be honest, so Moyes's brand wasn't all that bad).
Under van Gaal, there is a very clear definition on how we should be playing football. If it works the way he intends, it could be a brilliant and incredible style of football that we play. Unfortunately that has not been the case. Whether that is down to the Manager's unwillingness to tweak his tactics, players out of position, players not good enough for the particular brand of football or just players just too dumb to follow the instructions, I don't know.
So for style, I'd vote Moyes, but this is a results business, and van Gaal wins that one for me.