I also love Garnier 100%. I dye my hair blue black, and I found theirs to be very nice, plus it smells much better than most hair dyes.
Lately, though, I've switched to Nice 'n' Easy, because the last time I went to my hair dresser, she said I "don't have *too many* grey hairs," and since I thought I had none (I'm 23!), I freaked out and started buying grey covering dyes, hehe. But it's also very nice, and the after-color conditioner that comes with it makes your hair really smooth and shiny after you color. My biggest problem is that your hair smells nasty for a couple of days after coloring, but that's often to be expected.
I've also like L'Oreal Preference, though they don't quite make the color I like. The only dye I HATE is Feria, because it turned my hair into straw. Yuck.