If you are talking about combo fixtures,sun systems makes the best and yes they are more effective then straight hortilux or agrosun gold MH in either phase veg or flower.I only have the 800 combo and its a permanent veg fixture now,but the sunsystems 600 HPS 400 MH must really be a dream.First off,they have the lamps oriented end to end like it should be,growzilla orients their lamps side by side,phooey lol.Plus they are just large,cool running fixtures.I cool my hydrfarm 1K MH in veg but not my 88 combo right next to it,its much larger and runs much cooler.I use 1 K hortilux to flower with vertizontal hoods but I swear if I were to start over it would be 600/400s all the way,veg and flower.