"I do not always drink fuel injection cleaner, but when I do, I drink BG 44K."
I do not know all with regards to cleaners, but have done a lot of couch research. My opinion is that if you consider it as an overall "maintenance" item, not a "panacea" to fix a bigger problem that can be caused by many other things than just fuel delivery, then there are products that do get some results. As with any industry, there are many that exaggerate for marketing.
On YouTube there is a poster "ChrisFix" that tests Gumout, Seafoam, and Techron. There is also a long line of internet threads on why not to use them, or when and how often to use them (especially stronger ones like BG 44K), and shops using them (not as upcharges, but quick fixes).
OP's question is very general, depending on problem if for some reason just fuel injectors, could range from solving only by a real sonic clean on one end, or a few tanks of BP gas (who refine with lots of additives) on the other.