I've used both of those bulbs, though the ATI were 80w and the Giesseman 54w. I liked the color of the ATI better, the Giesseman looked kinda like a white bulb for me. In my current 6 bulb set up I have:

2 ATI blue plus
1 ATI purple plus
1 ATI actinic
1 KZ Fiji purple
1 ATI aquablue

I really like how it looks