Choosing my first quality knife.

[Hairlesstwinkie]

All of your options are assisted openers. Maybe look outside of those? Assisted openers are cool ideas, but at times they get dangerous. I have had a few open in my pockets. I would honestly recommend none of the above and go with non-assisted. When I first got into quality knives, I wanted just assisted, but now I can't stand them because of the bad experience. Go with anything Benchmade with Axis lock like Mini-grip, reg grip, mini-onslaught, Pardue, etc, they'll be as fast if not faster than some autos/assisted-openers with a good thumb flick same goes with some of the Spyderco lines with adjustable pivots like the Delica 4, Endura 4, Manix, Paramilitary 2, etc. Pop a zip tie on them and you can wave them. Most of those you can find right under $150. But if you MUST have an assisted then I would recommend the ZT.

 

[flarp]

Here are some side-by-sides that include the ZT0350, Shallot, and a couple others. The Cyclone is discontinued, but not especially difficult to find. The Aegis is the same size as the Flash II, and the Trident is a quarter inch longer.

Left to right: Flash II, Shallot, Blur, 0350, Cyclone

 

[ozgooner]

Of the ones you list, the ZT350 is easily the way to go. As noted though, it's not great if you have big hands (as I do). If that's you, then the ZT 550 and Spyderco Paramilitary 2 are both outstanding options.