You are going to find a greater amount of stratification for the 'organic' and soil-related fertilizers. You'll see less startification with soilless/hydro ingredients.
e.g. ingredients like magnesium sulfate, calcium nitrate, ammonium nitrate etc do not vary in quality by brand whatsoever. Whether you use some gardening brand epsom salt or walmart's equate non-scented epsom salt does not matter.
Other things that are well known concepts should be applied. The ratio of nitrates to ammonium, for example. There's a known synergy from having at least some portion of nitrogen come from ammonium nitrate vs something faster "acting" (lack of proper vocabulary, but the gist is correct) like calcium nitrate.. I believe it's something like 5% of the total coming from ammonium nitrate is ideal. You'd have to google why that's the case.
But, some amatuer brands may not be aware of existing knowledge of such things, and that's where you'll see greater deviations of quality... some niche-specific marijuana brand that never hired a biologist or chemist to properly formulate their products etc etc... and they make mistakes or miss out on benefits due to pure ignorance. A marijuana brand does not mean it's unprofessional, but there are definitely a few out there. Then, you got the greedy ones that break nutrition into 10-15 different bottles, when all you need is 3-4 to properly adjust to various life stage needs.
If you go soilless/hydro, i'd suggest Jacks 321... buy their "Part A" 5-12-26 and maybe their No-N 0-12-26 base and any generic calcium nitrate and magnesium sulfate (epsom salt) you can find at cheapest price locally. If you buy the 25lb bags, you pay about 4 cents per gallon or less. Running a 4x4 year round might take you 3-4 years to use up 1 bag of Part A.
It's ~3500 gallons worth based on 3.2g/gal usage. IT instructs a bit higher, but averaging out bloom and early vege it's probably closer to my use than as instructed. Even more gallons from the 25lb cal nitrate bag. It's dry, so it stored indefinitely. You can make 100:1 concentrations to dose out at 1mL per L or 1.28 fl oz per gallon - dealer's chouce as 1:100 is 1:100 either way.
J.R. Peters (jack's 3-2-1), megacrop, cropsalts, kosher salts, southern ag, masterblend, athena pro line, floraflex (at one time) all have a similar setup with similar ratios of nutes and same 3-part setup. Don't overpay for brand name on this stuff. They are all equivalents.. best price is the best product. Tip - watch out for where they put the trace elements... jacks puts it in part A, so all is fine, but other greedy fucks put it in the stuff you can get cheaper generics... e.g. if they stash it in th eparts you can buy cheaper generics, it forces you to buy their branded cal nitrate or buy some trace elements to add yourself.
It's a common formula because it's based on years of knowledge and experience. It's no coincidence that all these companies use a very similar formula.. it's adhering to the same knowledgebase.