Most of my own rules use IGOUGO - though I always add a limited ammount of reactive fire where appropriate, and keep the 'non phasing' player interested by opposed rolling (EG: One player throws to hit, and his opponent throws a dice to account for range - and possibly one for the effect of a shield or armour.)
I have recently started introducing an alternating Imove-Youmove where both sides shoot at the same time, but move alternately.

Having tried several 'Card driven' systems, I have found them frustrating very often.
I, too think SofG and WofG do very well in simultaneous movement, as does 'Beneath the Lily Banners' for the WSS.