When it comes to ZT, my default choice for EDC is still my 0350.
I like the ergonomics and versatility of this package.
My favorite is the 0630. I don't understand ZT doesn't offer more manual-no bearing-no flipper knives. They are great. The ergos on the 0630 are great
When it comes to flipping action the 0801 is my yardstick. I have a black and a blackwash versions with Elmax steel.
They are great but they carry heavy... maybe due to the design since the 0350 and 0630 are heavy too but I have a different feeling with them
The 0550 and 0562 are great but they have their flaws. The 0550 is wonderful but the locking side is way too thick. It will have been perfect with a locking side like the one of the 0562
The 0562 is great but I am not a fan of the grind... what a poor slicer
the 0450 are great EDC and IMO very similar to what the Benchmade 940 series offers. A little bit on the gentleman side but very capable and many options available
The 0909 and 0804 are very good if you look for something long and heavy

I think the 0909 is a better choice as a workhorse. Not that the 0804 is not capable but the price will give less regrets abusing it
I don't have a 0456 but it is very appealing if you don't mind the weight for the size
Their is so many good options at ZT , each Ines will have their spécificités and it will depend on you to decide which ones fits you better
My first ZT was a 0350 and it has influenced me. I like the robust and heavy feel of knives with a bit of tactical to it.
You may built a different experience and enjoy the lighter more gentleman-ish designs which are just as good (just different)