Since I have discovered the modern neck knife concept, I have liked it a lot. Neck carrying is very practical for many reasons but it has only (relatively) lately evolved into a specific concept. There are a lot of very successful concepts out there, the only problem is finding what suits you and your use in that tremendous offer. One of the main factors for living comfortably with a necker is its weight. And this is extremely specific to the person : too heavy, you're getting quickly tired of the knife, even if it performs great. Performance is paramount, too : too small / light, you're getting tired of it because it doesn't work so well at being a knife. Out of all the neckers I have acquired, here under are my favorites :
From bottom to top :
Fred Perrin Street Bowie skeletonized : amazing... a 4" + blade as a necker ! I'm a weight weenie (as far as neckers are concerned) but this is fabulous.
Fred Perrin Mini Bowie : even easier to carry and it masters all everyday small tasks with perfect ease.
Evans Knife and Tool Companion : not much additional weight, but comes with a substantial handle and a very strong blade. If your necker needs to stand up to some abuse, go for it !
A.G. Russell WoodsWalker : a very light knife with a very thin blade but a substantial handle to boot. Probably my N°1...
And... the ugly duckling ! The Cold Steel Sgian Dubh. Not the most convincing version of the mythical Sgian Dubh but a very successful design : light, handy, efficient and the best retaining action of all knives listed above.
And as this is a very important feature, I'll add that all the knives' sheathes above have satisfying retaining action. Satisfying enough to carry with confidence (although I do not advise to extend that confidence to mountainbiking or trampoline jumping...). The N°1 (by far) is the CS Sgian Dubh, closely matched by the A.G. WoodsWalker and the EKT Companion. The Fred Perrins are N°3 : reliable (never had a slip) but the snap feels soft.