I'd say 0550 also. Especially if you already have a 0350. I really like the way the 055x fits my large hands and it may not be your thing.
I find the 0550/0551 blade shape more usable also. The 350ZDP may have some collector value, where the 0550 is going to be more of a user knife.
My favorite knives are the 0550/0551, Blur, and Skyline.. with the Skyline getting the most carry because it is cheap and light. I expect the 0560 will replace
the top. I expect the Cryo will create it's own new category as it can't replace any of those and is Chinese made but looks really nice.
So, for a long winded verbose answer to a simple question.. depends on what you're use and fit needs are.