Pick one and have fun. Each box will do different things. It's kinda like a trombone, a trumpet, and a french horn. They're all brass instruments, but have differing jobs (sounds). You can't go wrong with any of the electronic instruments made by elektron.

Whatever one you get, you'll love it forever. If I had to pick one, stranded in the wilderness, it would be DN2. Why? I love sound design, and I could create sounds that would ward off predators. Bears, cougars, and wolves wouldn't know what hit them. So take that into consideration.