Here's my two cents worth. Like a lot of others, I collect some knives other than Bucks (Gerber fixed blades from the 60's and 70's). If we are going to do this, I think that posts should compare different knives and give specific advantages or disadvantages of one versus the other. Just posting pictures doesn't seem to serve much purpose.
OK.
I posted pics of some of my Opinels and I'll compare them to the Buck lock backs I own, adding some more comments to the differences I already mentioned in that post.
Technically, I find the Opinels to out perform my Bucks rather consistently. The convex grind on their blades is just amazing when it comes to cutting through wood. Whether its goofing around carving and whittling or cutting brush when doing yard work, the Opinels just simply cut better and I'm convinced it's the grind.
I find the Opinels tougher in terms of the integrity of the joint. The way the lock ring engages pretty much guarantees that when you engage the lock ring, any play in the joint is stabilized. Several of my Bucks have developed some amount of play here and there and that's just a non-issue with my Opinels. I should mention that I tend to use my Opinels harder than my Bucks, especially doing yard work. They're cheap knives and I use them like I don't like them but they just don't bust. After several years of beating on them, I've come to respect the Opinel and it's a respect that been really earned.
The big thing the Opinels fail at is that they aren't Bucks. Buck and Ulster/Schrade are knife brands that are riveted to my soul. They were both a big part of my growing up and (with Buck) my adulthood. At hunting camp, you carried a Buck, end of discussion.
I should say that not all Bucks are Bucks to my eyes. The core of Buck for me is the 110/112, particularly the frame. The newer models that don't maintain those lines look foreign to me. Nice knives, I'm sure, but Kershaw and CRKT make nice knives too and I'm not much more interested in the new Bucks than I am in the Kershaws. Not that they aren't nice and not that people shouldn't buy them. I'm speaking here entirely for me and why I carry what I carry. For me, the Buck I carry has to be somehow linked to memory of the first 110 I purchased in the 70s. The lines have to be there, the locking mechanism needs to be there. The Ecolites provide that for me, even when reblade with a drop point.
In the same vein, this to me is the biggest distinction between my Opinels and my Bucks. The Opinels are great knives but it's sort of like getting great French cooking. Good French cooking is great, but it's not the same as home cooking. My Bucks are more like home cooking for me (ditto Old Timers).