Our most popular rear derailleur by far, and the one that goes on about ninety percent of the bikes we build.  The reverse "rapid-rise" action means you move the left and right shifters the same direction for the same result. It's the way to go, unless you have old habits you don't want to unlearn, even though it's easy to do so.
Although "reverse action" derailleurs are (in the big picture) new-fangled, and also although we don't generally go ga-ga over newfangled things, this one has won us over. It doesn't require any lifestyle changes or committments; you just put it on, get the hang of it in anywhere from ten to sixty shifts, and from then on you forget about it.