Well I'm not hugely concerned about sharpness out of the box, since I can improve that.
But besides what was said - how it cuts through taller, harder stuff like a winter squash. Does it crack a thick carrot or a melon?
Performance at the tip - make those cuts through an onion before dicing. Any wedging? A thin tip is great for performance.
Design is important - note if it there is a flat section at the heel. Some people are choppers or push cutters, they will favor a large flat spot. A combination of height and belly is great for rock choppers. Some knives can handle both, but that is usually a 240mm knife.
Design - grind also helps with food release. People with any blade speed will like that. People who don't will get sticking regardless.
Design - balance point. Some people like a forward balance, some like a neutral balance. In prolonged use, a forward balance can be tiring. But it does give power in cutting.
Fit and finish - are the corners and edges (not THE edge) relieved/chamfered, or are they rather sharp? This plays into comfort and usability.
Weight, metal, HRC, height at heel, thickness of spine at heel.
Off the top of my head.
People with large hands tend to prefer taller blades, regardless of grip.