For many years all I used was a lansky to set the main bevel and a sharpmaker to do maintenance. I had good luck with that combo but wanted to see what I could add with other systems.
Over the past couple years I've messed with the edge pro, work sharp KO, wicked edge and there's no magic bullet when it comes to sharpening, they all have their pluses and minuses. One thing I've found is that while I can get a ridiculously sharp mirror polished edge with the edge pro or wicked edge compared to say the lanksy, those edges do not perform significantly better for me in my daily cutting chores, the same is true of fine grit stropping. They go through phone book or toilet paper better sure, but for me a 400-600 grit toothy edge with ceramic touch up works better on my day to day cutting chores my pocket knives see than a mirror polished super smooth stropped edge. The other thing I've noticed with many of these sharpeners they all work better on blades with large flat areas and less belly, many folding knives these days don't have easy areas to lay flat, or clamp securely. If you notice in product videos most of them are with nice easy kitchen knives with fairly strait edges. Documentation is also big, recording the angles etc. for each knife makes future sharpening/touch up much faster/easier. Here are my thoughts, your mileage may and will probably vary drastically.
Lansky: cheap and portable, and a pretty good edge, diamond stone kit still under $70, though I prefer the normal delxue kit with just an extra coarse diamond stone. The new version clamp is subpar compared to the old version IMO and it seems more of the plastic stone holders are warped as of the last few years. Not fun for big long blades. I still like it with a ceramic rod added for being a very good functional solution that's field portable.
Sharpmaker: Great for daily/weekly edge maintenance but I'd hate to re-profile an edge with it. Mine is very even angle wise but others have complained their base angles are off so that can be an issue. I honestly preferred the older sharpmaker base compared tot he new one that had just 22.5 degree slots for touch up compared to the 30/40 degree current base because I typically set my lansky at 20 degrees.
Edge pro apex: Gives amazing results, but it's time consuming, messy, and high maintenance. Works best on knives with large flat sides. I could never get used to one hand holding the knife solid, moving/rotating it, and running the stone with the other hand, and then trying to do the reverse on the other side of the blade, too inconsistent. So I used the magnet trick and don't move the blade and make angle blocks to keep the blade at the same angle. It's messy, I've found a lot of folders I do I end up having to tear down clean the gunk out of the pivot area, lube and reassemble. You also have to do stone maintenance flattening the stones. I have a couple folders where due to thumb stud placement you can't get the stone to the rear 1/2" of the blade without hitting the stud. On the plus side you gets TONS of versatility, lots of angles, tapes, stones galore, strops, basically anything you can attach to the 1/8" thick aluminum slab you can sharpen with. I've had really good luck using just the Congress stones in various grits that others have recommended.
Work sharp KO: it's fast, did I mention it's FAST! You can take off a ton of metal in a short time, even without the coarsest grits. This is good and bad

I love it for kitchen knives, and knives I'm not "attached" to. My technique needs work I can't get consistent angles on folding knives with thicker blades. If I set the guide to 18 degrees I consistently end up with 16/22 instead, which result in an edge I can't use my sharpmaker on easily. I don't have the tip rounding problems others have mentioned in fact I think it's very easy to keep the tip pointy as long as you don't go off the belt. I can do a full set of kitchen knives more than sharp enough for me in just a few minutes, that alone is worth the price tag. The stock set of belts does a pretty nice job and even puts on a pretty nice polished edge. For those that are impatient at sharpening but patient enough to go slow at first and learn good technique it gets impressive results faster than anything else. A few minutes with most folders and you can not only re-profile, but polish an edge, a few finishing swipes on a sharpmaker and it's an impressive edge for the time invested. I can see how over time a person could really take a lot of metal off a blade though if you were not careful about touch up/resharpening only being with fine belts.
Wicked edge: I see it as a lanksy on steroids, which isn't a bad thing. I'd prefer to see the mount angled back toward the user at 30-45 degrees to get better access/view of the tip/belly of knives, which can be done with an angled base. Diamond stones are a plus, lots of strop/stone options and you can buy blanks for your own as well. I'd say it does as good of a job as the Apex does, only with less effort/mess, I think of them as Canon/Nikon I think most users will naturally gravitate toward one or the other. However, it's still a clamp and has all the issues that come along with trying to clamp blades that don't have flat areas. It also has the issue of changing angles along the tip/belly but that can be minimized with proper blade placement in the clamp. Lastly, it's $700 for the full kit with the upgrade hardware/pivots. You can buy the full kit of every other sharpener mentioned here and still not spend that much.
One thing I've learned is that if I'm honest with myself, for everyday pocket knife use, none of these expensive sharpeners really added THAT much to the results I was getting with the Lanksy and Sharpmaker combo. I gained some edge/angle consistency and the capability to go to a much higher polished edge and more sharpening angle/stone options, but as far as real day to day cutting functionality it didn't change that much. Admittedly part of that might be my fault because I'm not going to spend weeks/months testing various edge angles/types/etc. etc. to squeeze out every last bit of cutting performance through sharpening techniques but that's my shortcoming not the sharpeners.