I'm very fond of neck knives, and I have a few of them. I even have some "non-neck-neck-knives," which means I have a kydex sheath for my Spyderco Delica (I got it from the now-defunct but was-very-good Ironstone Cutlery catalog). I also have a cheesier one for my Spyderco Lightweight Walker Linerlock (not as secure as the Delica's sheath).
I'm always shopping for a new neck-suitable knife. I recently ordered two Timberline Mini Pit Bulls (they should arrive tomorrow if the UPS order tracker is worth anything). They have a great shape, and look very simple and no-nonsense (that's my big preference).
I also just saw the Boker Bud Nealy Specialist II at Knifecenter.com and it looks SWEEEEEET! Of course, it's $100 if you get the G-10 handles, but only $49 if you get the plastic ones. (I'd want the G-10, since they appear to be removable with hex screws.)
I lean heavily on my CRKT Neck Peck, and my Cold Steel Spike, both of which see daily carry rotation. I also have a Benchmade TK-1 (Tether Knife) which, while I LOVE IT IMMENSELY, I don't wish to carry. It's more like a pride-and-joy to sit in my trunk 'for the enjoyment of having it.' It's actually my favorite, but until I can afford a second one (at something like $70 a pop!) it won't see use.
I just looked at the La Griffe and have to say I don't care for it at all. I simply don't like recurve blades, because I see their use as very limited. (That's also why I don't like fully serrated blades.) The Spyderco Spot is also in that category for me. HOW I would love to like a Spyderco neck knife, but they just didn't hook me with the weird-ass recurve blade. It looks like a Civilian Mini-Me! Those spots do nothing for me aesthetically, and the grip orientation looks troublesome, and the knife looks *weak* overall.
I really would recommend the TK-1 or the Mini Pit Bull. The former is rather expensive for a neck knife, and the latter is about $28; your other choices leave me puzzled about whether price is an object ($58 for La Griffe & about $20-something for Arclite). I think the bang-for-buck factor goes to the Arclite, given my feelings about the alternative La Griffe, especially for their respective prices (and who wants a french-named knife?!)

But there
is that Mini Pit Bull...