Mmmmm.... great question.
I do shoot Canon, but apart from the 430ex I use on the camera, all my other strobes are Nikons. My bag has 8 lights in it:
430ex (Canon)
3 SB80dx's (Nikon)
2 SB600s (Nikon)
2 SB24s (Nikon)
The SB80dx's are the greatest speedlights, ever. They cost about half of what an SB800 costs, they have the same GN, and despite what the specs say, they are almost as fast recycling. And, best of all ------- they have KILLER built-in optical slaves. The optical slaves on these things will work at outrageous distances (indoors), even around corners and up stairs. Outdoors, they suck. But I don't care about that.
For the other lights, I'm using
cheap radio slaves. Pocket Wizards would be great, but I don't have the budget for them, yet. And these "Poverty Wizards" are actually very good, although they do get mixed reviews.