Having not read the entire thread, I will go out on this topic.
Mayo is right, you buy the best you can afford. You only have one life.
You do not buy a folder for combat or conflict purposes. Mr. Murphy tells me the lock will fail to engae or hold as you try to open it under high duress, you get a fixed blade with a sheath made for your use, belt carry, drop leg, IWB whatever your use is. You must be able to securely retain and carry your weapon while maintaining the ability to retreive your weapon in a hurry (immediately) You get a sheath that works for you in everyday use. A shoulder holster is a pain in a winter jacket for instance.
You get a point that will withstand impact with bone repeatedly.
You get an edge that is durable and easy to resharpen. You get a design that can cut and thrust within your needs. If you want a stabbing implement, do not buy a blade with a huge belly you could skin a water buffalo with. If you want a cutter, it needs to be able to take a wicked cutting edge but not entirely razored edge, as a thin razor sharp edge is going to chip off and dull the moment it hits a hard target.
You get a grip that is on the large side as opposed to small with ergonomics and texture that will remain usable when your hand is cold, wet and covered with blood (think MOTOR OIL ALL OVER MY HAND ON A COLD DECEMBER DAY) The grip can have whatever configuration you want as long as you maintain control over the weapon during use.
Most important, if this is to be an everyday weapon (carried daily) it needs to be a size big enough to be effective yet samll enough you will carry it every day. Bigger knives weigh more than smaller ones. Bigger knives like bigger anything takes more toll on your back and body on a daily basis.
My personal recommendation, what I carry, is the Mad Dog Rat series or the Mini Shrike followed by a Busse or a MOD Razorback. I carry the MDK Mini Shrike on a more or less daily basis IWB or in the briefcase outer pocket. I have another Busse 3 on the way, which I just traded off an Entrek Companion Spearpoint to get. The entrek is another high recommendation.
In terms of bigger knives, try the MDK Attack, the Randall series, or the busses and Chris Reeves. I also own one of the CS Tantos, I like the blade and handle, but the sheath is POS regardless of what they are shipping currently. If you go this route, hve a good sheath made, Frank Sigman or Blade Tech are the way to go.
Stay away from cheap junk or designs that do not work for you doing everything you need them to. Additionally, invest in a good Swiss Army knife, Victorinox, in the same pattern as the old Boy Scout knife and use it for as many chores as you can. it will save your primary big blade for its bigger mission and you will also be able to have a beer or soda now and then with the bottle opener.