As someone who owns the ARC AAA-P, Solitaire with Tektite LT-3, and Peak Matterhorn, if forced to choose only one, it would be the Matterhorn. Why?
1. ARC is the smallest, but it loses because:
a) my ARC's "super-hard" anodizing scratched right away when I pulled off the pocket clip. That's tough???
b) The ARC's knurling is very aggressive - it's so "grippy" that it takes an extreme amount of force to pull it out of the little pocket on the side of my Nite-Ize cell phone pouch - whereas the Matterhorn and Solitaire go in and out much easier. I don't like it as a keychain light, because the aggressive knurling scratches up anything plastic, such as remote control, keys, mini compass, etc.
c) although the ARC AAA-P is a wee bit brighter than the Matterhorn, the color sux. Bright purplish hot-spot, surrounded by a sickly green-yellow corona. The Matterhorn is a very pleasing white.
d) The ARC AAA-P is $5 more WITH an 8 week backlog.
Both the ARC AAA-P and the Matterhorn are superior to the Solitaire/LT-3 combo. Don't get me wrong, I am not an ARC hater. The AAA-P is a cool little device, and a 1/2" smaller than either of the others. It is also a "cult classic". I just think the Matterhorn is a better "overall" package for what it does.