ESEE Izula is a great starting point to help you figure out if a Necker is for you. Not too expensive, very versatile and a great warranty. I've carried mine for many months.
My GO TO EDC necker is my Murray Carter though. That thing is a better cutter and slicer than any knife I've used...
Here they are side by side...
As far as the argument on whether neck knives are a practical carry method or not, I will never EDC a fixed blade any other way. There are a few things to keep in mind...
You want the cord or chain that you use to be just big enough to get around your head. This helps it stay high and tight, and prevents a lot of the swinging that other people complain about with neckers.
Also, if you are in a situation where it is acceptable to wear the knife on the outside of your clothing, such as when hunting or fishing or around the house or even at work depending on what you do, then I firmly believe it's the fastest way that you can deploy a knife. As soon as you get your hand around the handle, the knife is ready to use with a quick tug. Even when it's under your clothing, it only takes a little practice to develop the muscle memory to retrieve the knife and deploy it quickly. It can be done very fast.
Also, with a belt knife or a pocket knife, if you lose your pants, you lose your knife. Not the case with a necker. If you are wearing a shorts with no pockets and no belt loops, still not a problem for a necker. If you need to change quickly, your necker can stay with you no problem. Don't have to transfer stuff from your pants.
There are many reasons I love it, and most people that don't like don't give it enough of a chance to become part of their EDC rotation.