I'm sure you've already checked your local laws about fixed blade carry and acceptable length and design, here in Texas, you can carry a fixed blade but it cannot be designed for killing, ( double edged, designed as a dagger etc... ) go figure. I believe the fixed blade can be 6" but a folder only 5".
My recommendations are, the neck knife and a folder, and use them as often as possible for a while to teach yourself where they are and how they oriented, do the neck knife with tee shirt and button up. By using them I mean draw them a lot around the house, don't go using your defense knife for opening boxes. While practicing with the neck knife, tape up the edge, it's too close to the good stuff to have an accident with, of course remove the tape when finished practicing.
The fixed blade knife can have some cool features, like a full quillion to prevent your hand from slipping up the handle into sharp pointy end territory. Got a friend that did that with a Cold Steel and it was ugly, could not perform his job ( cop ) and could not shoot for 2 years. It severed all the tendons and muscles to the bone, from the inside of his hand.
I carry 2 folders, one is for everyday chores, it is a spyderco EMT knife, blunt nose, fully serrated for cutting seat belts and such, 3 1/2" blade, blaze orange handle. The other is a cold steel voyager with a 5" blade, very sharp and it is only for cutting something wide and deep, not for any chores, your defense blade should always be ready for flesh, nothing else.
If your interested in upper tier fixed blades, I do have a Cold Steel San Mai Tanto with 9" blade and a Sure Fire Echo, both with sheaths for sale, well under retail.