Do I have to choose just one? I have about 10 handles in my box and on a normal day of flying I typically use at least three of them. Starting at the top left and working to the bottom right...
Aldrich Magnum handle, modified with bicycle grip. Probably my first choice. Simple but effective, fairly tight line spacing. I usually only branch out from this one if the control system is too sensitive and I need tighter spacing.
EZ Just "Hot Rock". This one sets the standard. Really puts the nostalgia spin on a vintage design. Doesn't lend itself well to a safety thong.
Smith Hot Rock+. Does the same job as the previous two. A nice substitute but the line adjustment locking system tends to damage the cable.
Homebuilt Hot Rock. All the benefits of the above, but again the cable tends to be a problem.
I think this one is a Brodak. Not entirely sure. I've got a couple of them and they're well made. Nice adjustability. Not my first choice unless I need the narrower spacing.
RSM/Hobby Fasteners. Again nice adjustability, the grip it came with wasn't very comfortable so this one was cut from Maple.
Not sure exactly what to call this one. It's completely constructed of aluminum and steel, with a bondo grip to provide an ergonomic benefit. It's impossible to pick it up wrong, and its very unlikely to come apart under the heaviest loads. It tends to be heavy I've never gotten comfortable with the grip.
Last is the simple EZ Just. The spacing is way too far apart, but its the handle I learned on and it still gets used once in a great while, when sensitivity isn't an issue.