Either. Two great yoyos.
Which one is physically better?
Um. Physically. They’re both bi-metal. They’re both USA Made. And they are both going to cost you $130+. They’re both yoyos. They come in cool coolers. They’re of high quality.
As for which you will like, I have no idea. Listing your preferences helps.
I have both -as well as the Phenomizm. The phenom is absolute trash compared to a Diamondback!
The Phenom is very light, very thin, fast, not the best gap-shape, and has very tight response with normal thickness string. And is not any fun to throw.
The Diamondback is one of my favorite playing yoyos ever. Perfect weight, great gap-shape, fast, thinner than most, BUTTER SMOOTH PLAY, and very good response with slightly thicker than usual string.
All in all, they have a somewhat similar feel to them, being thin metal throws.
In terms of preference, Diamondback hands-down!
Note: I got both second-hand, VG condition.