Ahh, very well then, I shall offer you my opinion.
I have the ArcLite, and my Cop Buddy carries the Stiff KISS. I found that the carry system of the KISS is indeed versatile, but I personally can find no use for most of the carry options the sheath allows. Cop Buddy does though.
I also find the ArcLite more comfortable to use, and I find that the blade shape is more comfortable FOR ME. Cop Buddy says the same.
The steel thing seems like it is gonna be hashed out for a long time, but I have made up my mind about the 420HC as it comes out of Camillus. I like it. I find that it performs BETTER than the 440A that is on my Kershaw Blackout. Yes, I've heard the arguments..... different blade profile, different this, that, the other stuff. My experience tells me that I like it better.
I haven't done any prolonged cutting chores with either of the knives. I use the ArcLite as a hang-around-til-needed piece, and it performs small miscellaneous tasks as they come up. Cop Buddy uses his for same, and he says it is up to the task. As purely personal OPINIONS, Me and Cop Buddy both like the ArcLite better.
Price on both is so close that it doesn't matter. Now here's another reason why I think you should buy both. You can be sure you have the one you like the best, and you can give the other to a potential knife knut friend of yours. Gotta love givin' knives, my friend. Gotta love it.