Gerber Covert - the dagger grind was pretty much crap utility wise. Should have bought the less sexy flat grind.
Largely due to being in Spyderco's collector's club, I've had the opportunity to try most or check out most of the models in the lineup. I haven't used the club to collect everything, but rather I've been looking for the "one" knife. I keep the "one" until something better comes along, the old "one" gets sold. I'll limit myself to commenting on the ones that I'd seriously considered for contention or used for awhile. These aren’t all in order:
Larger Wegner - My first Spyderco. Very impressive feel, and heft. Ultimately the large belly, high point, and hollow grind let me down for my admittedly "gentleman’s" needs. This is where I learned to dislike hollow grinds.
Bob "T" C15 - I lucked into one of these. I treasured as an object. I found the ergos and blade profile to be perfect for EDC, but the saber grind was another let down. I passed this on to a friend who's a Sebenza fanatic.
Carbon Fiber Police - This was a beautiful piece. Carried easy, great point, but for serious cutting the hollow grind as usual was an issue. Ultimately really just too large, esp. for something where only the point was useful for me.
Plainedge Rescue - Thin, light, cut like an absolute laser for light duty. Loved the straight edge. The lack of a point retired it. Hated the barrel-bolt clip too.
Carbon Fiber Civilian - A really magnificent piece. Was very surprised to see that Sal had listened to me an added the tip-up carry option (thanks Sal!

). I have no criticism of the knife itself, other than by carrying it, I learned that I didn't like to carry a weapon.
Grey Matriarch - got this one used from Sal himself (thanks Sal!

), but it went with the Civilian for the same reason.
Military - just too damn big.
Native III - I really liked the handle on this knife. One of my last real attempts to make nice with a hollow grind. Didn't work for me.
Assist II - Took the FRN handled knife to a whole new level. Loved the wharncliffe point - this got me really looking at wharncliffes. The whistle really didn't work for me. Don't care for the Hood. Not really into serrations either. Finally it was the overall size and bulk of the piece that shifted me away. The wire clips on this and the Native III were great.
Meerkat – Really a nice little handful of a knife. Phantom lock was very easy to use. The wire clip failed me and it went back to Spyderco. Reverse-s blade profile was so shallow that it didn’t seem to offer any advantage over the drop-point. This one ended up being too small, and too bulky for its size. And I don’t like tip-down.
Lil Temperance – I’d loved the look of the trailing point and had really looked forward to getting one. But once again that high point and lots of belly fell down a bit for EDC. And it is a very bulky and heavy thing for the amount of blade length you get. Fine for an MBCer, but a drawback for light utility use (which it isn’t intended for). I didn’t bother trying the leaf.
Impala – all the same issues as with the Wegner. You’d think I’d learn. Don’t care for tip-down either.
Salsa Ti – Having had to sell my beloved and perfect Lum Chinese folder due to new draconian carry laws in Boston, I’d really looked forward to this. But on my first run model, the wire clip was too tight, and the detent failed to keep the blade closed in pocket or on the draw – especially with the hood trying to wave it open. I found the hood to be an unnecessary addition. Also the lock bar traveled over very quickly with EDC use. This soured me on framelocks a bit. I had it factory serviced then passed it on.
Almite Navigator – the slots in the handle made it very uncomfortable in the hand.
Shabaria – I like this one despite the hollow grind. I recall being annoyed with tip-down, but I think it went because it just wasn’t quite what I was looking for. I think at this point I really began looking to knives with about a 3” blade.
Ayoob – this one was like a SS Police. Thin and easy to carry, great point, and that’s it for me. *&*(^! tip-down. %^$%! Hollow grinds. Too large for my EDC.
Spyderhawk – It had at least some utility use, if awkwardly, but at the end of the day it was a weapon, and I didn’t feel comfortable carrying it, and it went.
Schempp Persian – From all of my prior experience I knew it wouldn’t work for me the moment I saw it, but it was too pretty and refined to not try it. Oh well.
Dodo – the only hollow ground knife I liked in EDC. No real criticism other than I liked the Para better for EDC when it came out, which retired my pair of Dodos. The Para was just a more comfortable and natural extension of the hand for all cutting tasks. And with no blade length restrictions in my current locale, there’s no need to put up with the limited (though great) ergos, and more specialized blade profile of the Dodo.
WT Kerambit – I was looking forward to this one, and it is a gorgeous knife. But the moment I held one in my hand my gut reaction was “brass knuckles.” It really struck me as being a pure weapon, and so it went unused.
Para-Military – This knife really redefined EDC utility for me. My only complaint was tip-down only carry, but which is at least partially own fault, so I can’t complain too much. Though I haven’t actually sold it the arrival of the Yojimbo has pretty much retired it. The straight edged 3” blade with its lightsaber point, and straight handle ergos took me one step closer to my unseen and still undiscovered ideal. I can’t say anything against the Para, the Yojimbo just suited my uses better, and sometimes you don't know that there could be a "better" until you happen upon it.