When working thru the technological changes over the last 35 years some things came to hand that seemed to be better than others. We can suggest a hundred knives but the real issues are materials and shape.
Blade steel - there are lots of new custom alloys out there but for the most part a medium cost stainless is the best value. 154CM or ATS134 gets the job done well with the least amount of resharpening, plus isn't a bear to touch up like the higher cost alloys. They work with you, not against you. I have a high end knife with S30V steel that has an incredibly hard to dull blade - but it's equally hard to resharpen. Steels that resist abrasion also resist sharpening, as that is just controlled abrasion to gain an edge. Be thoughtful about what you ask for.
Edge geometry has a big influence, a flat ground blade is generally better at full cutting as there is no swedge grind to jam into the cut. Some think that a heavy blade is needed for hard use but the down side is that it becomes more and more a sharpened pry bar - and if that's the job, a sharpened pry bar does pretty good especially with a hand sledge. Since it's a folding pocket knife and not a collapsible piton for extreme use the thinner blades cut better and have more control. The tip design is something a lot of makers are playing with these days but for the most part a simple drop point gets it done across the board.
The frame construction has become pretty standard, two slabs of metal with a large pivot pin and ferrules to space it. What material raises the cost exponentially, and whether its skeletonized affects weight. Titanium frames are nice but not cheap.
Grips are the part you hold and feel, metal grips in aluminun are cold to the touch and can be slippery. A lot of higher end knives use G10 now and with a gripping surface they are warm to the touch and hard to drop. They can also be too abrasive to pockets and it has to be balanced - a seriously checkered grip can and will cut a slot in a jeans pocket quickly. Large crosscuts and jimping on the blade and frame back can assist in gripping - or they can be too much and create friction points causing blisters. It's very dependent on the user and his interaction.
The lock has narrowed down to the traditional back lock, which is somewhat rare these days, the liner lock, frame lock, and Axis lock. In the better grade of knives they all work. It becomes a matter of habit which is preferred, and despite the tactical talk about which is best, it boils down to the issue of having to - in extremis you only have a pocket knife anyway. Good luck with that. A knife is better than no knife.
Along with that is tip up or tip down. A lot of people decide on that matter based on having stuck their hand down into the pocket and finding the blade open. A good knife shouldn't do that, YMMV. It happens.
That brings us to the clip - which most modern using knives have had for over 25 years now. Mounted high on the grip or lower to expose more of the butt is another feature some have a preference for - or not. Knives that have alternate mounting points offer four places to carry which allows tip up or down right or left handed. All those pads and screw holes do affect the aesthetic look to some degree.
As for spring assist the choice is based on your states legal requirements and how they are enforced by local LEO's. One state may prosecute for carrying a normal Buck liner lock visible to the public, another may allow concealed carry of an automatic. I'm happy to say my state prefers the latter. The majority of states seem to allow assisted opening. How the knife opens in any fashion goes to thumb holes, studs, or discs on the blade, a button lock, or extended kick protruding out the back of the frame. If anything there are almost too many choices now and varying levels of having a secure grip doing it. And if spring powered the makers are currently using higher pressures which snap the blade open with some force. You have to hang on now, a light grip will lose the knife.
The largest part of the market now is under 4" stainless blades with liner or framelocks, black grips, and $100+ pricing. For the most part those were rare knives 15 years ago but are dirt common today. They are good knives overall, the problem is choosing one tree out of the forest. Look to what features you want and narrow by those and it will help sort things out - then go find them and actually put your hands on one. It can make a big difference when you handle them.