it possibly depends on the game, but i don't choose one or the other. keeping both in mind, imo makes you win games. In multiplayer games especially.
knowing when to react and when to "proact" is key to winning.
easier said than done!
i play world of tanks, and it helps knowing the map very well to more quicker know when to be reactive and when to be proactive. so my tip would be learn the maps.
GLHF!