What has been your most satisfying component?

I don't think I have seen this question asked so here it goes. Many of us tend to buy and sell looking for the ideal, the holy grail, what works best in the current system, or whatever.
What component (or components)have stood the test of time in your system? I've been through quite a few but some have stayed despite having bought their replacements and subsequently selling them. I'll share once we get a few posts to get things going.