Between the 0300 and Adamas, I would take the Adamas without a doubt. Most of it is personal preference. I much prefer the Axis lock, smooth manual opening and closing action, and the ergos. I also prefer the blade shape of the Adamas.
The 0300 is a great knife, but it has very sluggish assisted opening, the tall recurved blade, and I'm generally not a fan of ti frame locks. If I were set on a ZT, I would get a 0200. Equal quality to the 0300, manual opening, and around the same price as an Adamas. However, you still get that insane recurve. Fortunately, since Ken Onions departure, most new ZT designs have done away with recurved blades.