Each of the opinions has merits. If you don’t have the talent or experience to tune an older (or new)plane your best option may be to find another, more experienced woodworker in your area to help you bring your skills up to speed. At least check out all of the available videos on restoring older woodworking tools. You really need to add those skills to your skillset because all (even high-end planes) require basic maintenance and the ability to troubleshoot minor performance problems.
I have worked with wooden hand planes, “transition” planes, older metal planes, new cheap metal planes, middle level metal planes, and some of the “high” end planes. They were all basically capable of performing the task they were intended to perform when properly tuned, even though there were some obviously better at their tasks than others. The experience (and time) made the difference between a plane that worked and one that didn’t. For those without the experience, “higher end” planes reduced (but did not totally remove) the need for fettling and normally made the process of use an easier experience. Past that, many of the fine points then become a matter of personal preference. To illustrate this concept I have on several occasions bought absolutely horrible new (and old) planes and have tuned them to perform surprisingly well. I don’t use them regularly because I have better performing tools but I do delight in bringing them out just to show to woodworkers who believe that throwing money at expensive tools translates into fine work. Do remember that rough tools can easily do the rough work and the finer tools are best reserved for the finer work. For most, older Stanleys, Record, Union, along with many of the other similar brands are a better option overall. I remember when I first started that I thought that all planes should be set for a thousandths or better shavings. That was before I realized that you were better off hogging off that quarter inch of extra stock using a different system and that wide plane mouths and cambered blades helped you get the job done efficiently.
As in the rest of life, your past experience and circumstances will determine the best course of action for you and the older Stanleys are often the better compromise between cost, quality and skill. Taking a cheap plane, old or new, and going through the fettling process (after you know how a well performing plane should perform) is of more long-term value than simply owning a high performing (when new)plane.
Just remember that oft repeated statements are not always true. Some of the post WWII planes with kidney shaped holes in the cap irons are actually excellent performers and are machined well. Some of them produced in the 1950’s and early 1960’s have heavier castings, and the larger brass depth adjustment knobs make use easier. Some older (very old laminated and tapered and some sheet) blades were NOT necessarily superior to modern blades. Modern blades also are generally more consistent but brand new blades sometimes will be somewhat softer at the factory edge but will improve with repeated sharpenings.
It all depends on the tools, the individual and the circumstances. If I was looking for a tool to use as a true jack, or for scrub work, didn’t have a lot of time for hitting flea markets or estate sales, or lived in an area where woodworking tool availability was very limited, then I would consider one of the “big box store” options.