That is the question !
It depends how you see it, wether it is the one you preferred to build or the one your prefer to use.
Personally, I could say the one I preferred to build is my OWT / router plane, and I like to use it also, but that's quite rare.
One of the tools I am the most pleased to use, because it's really efficient and makes the difference, and I use it nearly every day when I'm doing woodwork, it is my Japanese style hammer, in conjunction with Japanese chisels.
Homemade Japanese-Style Hammer
I must admit I built it more for the fun, for the look, etc ... and it turned out to be one of the most useful and efficient tools.
But it is also forgetting my bench, which I use even more frequently (some in my family would say I even sleep on it, but that's not true !)