FWIW - what you are really asking is, who makes the best open end.
If you are looking for a wrench performance upgrade (I would define "wrench performance" as strength, design (accessibility), ergonomics/ease of use), the long pattern double box ends are the way to go. I have Snap On. ICON make a copy set, but various other brands out there make them, KABO, etc, all for significantly less money than Snap On.
If you really want combos, read this
thread, but beware of the rankings. Many of the top brands many of us know and love, lost out in the strength test to thicker wrenches (such as Wright Grip). The numerical rankings strongly prioritized strength. So you might want to look closely at the data (specifically hardness and strength/thickness). The quick answer is, Snap On remains top dog. But because "top dog" comes at a "top price", is that the best option for you?
If you've got plenty of money and just want a great set of wrenches, the long pattern Snap On's SOEXLM represent a significant performance upgrade over, probably, all wrenches ever made. Their business ends are thin and tenacious, and their length can help reach areas and provides a little less fatigue to use. They are my daily drivers for automotive. But I would say, I also have 0 and 15 degree double box ends, what Snap On calls their "hi performance" wrenches. That is a descriptive name. I use those pretty frequently as well.
If its an automotive application, I'd vote Snap On combos, I have a preference for long, but you choose, then I'd pick Snap On's "hi performance" double box ends in the sizes you need for your most likely application. Snap On seems to be favoring the Asian car mechanics with their sizing offering 10-12 12-14, pretty sure 14-17 BDE.
14-17 confirmed! It's in my roll cart! (top wrench in pic above)
Snap On if you are listening, the DBE combos are nice, but why not offer some for Euro people? I'd like a 10-13 please. 15-16 makes a lot of sense for US cars. You will get it wrong every time, but at least you have the right tool in your hand.
The set of wrenches above has been a very capable, and can be recommended. I bought all these wrenches second hand and they were pretty cheap at the time. My main box, well here it is here...
...has the long combos. You can compare them visually with the ratchets, upper right. Note a full set of the 15 DBE is only 5 or 6 wrenches, so maybe a pretty good value?? if such a thing exists from Snap On. The 0 degrees (top left) are coupled with ratchet ends I don't trust and don't feel great to me. These are an older generation. That said, the idea is sound, crack it free with the fixed end, then flip the wrench to finish.
Even for simple jobs like replacing a Honda alternator, I was in this box to find a couple silver bullet wrenches. The idler/tensioner pulley is just inboard of the frame and pretty hard to get to from above at least. I think some modern cars are legitimately designed to be maintained by people with lifts etc. It's accessible, just not
easily accessible. Thus the special wrenches.
So, full circle, when you talk about "upgrading" wrenches and "quality", if you are talking about finish quality, maybe Nepros is what you are after. I hear they are jewel-like. If you are thinking about a "wrench performance upgrade", you need to read this post again and ask (yourself, then us) some different questions. For example: What constitutes a "better" wrench? Is the strongest wrench the "best" wrench? What features of the design of a wrench effect us most? Is length the attribute we respond to most (i.e. more than strength? Or how it feels in our hands? Do you hit your wrenches with hammers (I do not, tho I have). I think most of the wrenches in the test are stronger than we are. Unless you are hitting your wrenches with hammers or using extenders. they are likely all "strong enough". Point is, don't let strength alone be the only measure of a great wrench.
My solution was to buy everything. So I get to pick and choose what works best for me on a case by case basis. This is not efficient. But for me, my "speciality" tools (including and especially my beloved FHLF80 and SHLF80 ratchets) are less about their functional performance and more about where my hand has to be, and how bent my back is and for how long. I literally can not be doubled up over an engine bay for hours anymore. I know it's a little counter intuitive, (like to hear others opinions)
when access is tight, sometimes longer tools are better. They get your hand to a place where you can be comfortable. So my box has a lot of long tools for that reason, particular long extensions, wrenches, long handled ratchets etc. For me
length is a performance discriminator.
Sorry for the long post, hope this helped.