Logitech vs. Razer vs. Saitek? which is better for gaming?

I prefer Logitech, they have the better keyboards without a doubt, The Razer keyboards got too concerned about looks and not enough on quality. For mice, Razer is pretty good, and I've owned a few of them over the years. They do have some annoying issues like sometimes after a crash or incomplete shutdown, the mice go unresponsive until you unplug and replug them, I think it has something to do with their "synapse" buffering design. As for the G9 mouse I currently own, I haven't used one better yet. I like the flywheel type mouse wheel, though I admit it isn't optimal for some games.
As for Saitek, their peripherals are okay, definitely aimed at budget prices. I'd say they're about on par with OCZ's offerings in the peripherals market. One place they do very well in is joysticks, but this isn't a widely used peripheral these days. Only so many people play flight simulator type games these days it seems.

I think the G5 is the best mouse ever made

Others like wathman prefer the D9. Best Keyboard is G11(on the budget) or G15.