Each have it's own good and bad.
I started riding with a front disc, just because with a disc brake you do have a little more control modulation wise, either slowing your wheel down or stopping it completely, but I personally didn't think it was powerful enough. - I ran a hope mono trial
However with a rim brake, either Vee or hs33, I found it loads better for bite and power, probably because I wanted it as good as my back brake - but it is difficult to modulate a rim brake, especially if you're running a grind and can be a pain riding down hill
I personally find rim brakes better for me, but everyone is different so i suggest at least try maggie on the front and if you don't like it go back to disc.