I can't give a direct comparison as I have never ridden the DRZ. But I have ridden other dual sports and used to own a KLR650. And I currently own a Himalayan (still early days and I'm still getting to know it).
I am sure that DRZ engine is a peach. I have had one Suzuki thumper and the engine is bomb-proof. Don't expect the same Suzuki quality in the Himalayan. But that said, I find the "relaxed" Himalayan perfect for my style of riding. Don't think of the Himalayan as a true dualsport in the same class as the Japanese bikes and you'll be fine and won't be let down. The Himalayan is capable off road, but not nearly as much as the DRZ is. If you are OK with that, and OK with a low-revving but very tractable engine that will pull you through just about anything, then the Himalayan might just be for you. For me, the Himmy is a perfect fit... comfortable ergos and capable for what I intend to throw at it. It has one annoying quirk that I'm still trying to figure out (a battery discharge issue), but for the money and for what it is, I'm happy so far.
It has enough horsepower for me, but that is a personal thing. I've had bikes that were 40-70 hp, and they were just too much for what I wanted. Even if RE produces a 650 twin Himmy, I'd have no interest in it. To each their own.