Have had yellows on my last three cars (all used on track). For the money they are, I won't be changing anytime soon. People will come along and say this that and the other are better - and they could well be, but i guarantee you they'll be more money.
You'll also get some sage saying he tried the Greens once and they were crap, or the Reds weren't up to track work. they'd also be right, but the Yellows aren't comparable in the slightest to either of the other colours/compounds.