Filters, I agree with.
Plugs and oil - well....no.
NGK definitely out perform the equivalent Champion in my classic Triumphs in terms of reliability for example - especially in a 2.5 PI.
Oil (oil again ) - I'm quite particular about the oil I use. Despite being labelled as the same viscosity, not all oils are the same. Sulphur content, the API rating all come into it, both in classics and modern engines. You probably won't notice any difference short term, but over time.... I thought members on here recommended GM 10/40 for the Omega for example?
Would you consider putting Asda Value oil (just as an example, although I'm not even sure that they still sell it?) that is probably recycled, into any engine? Maybe as a quick flushing oil, but that's about all it's good for.
GM oil was recommended because it was a quality product at a
really good price if you could store the extra. Anyone with connections could get similar deals elsewhere, and the cost/value/convenience overlap changes. The impressive part of GM's Trade Club was the extremely easy access to it: the local Toyota dealer closed our trade account(workshop deliveries only, and had to be paid through the account) because we didn't use it enough.
For many years I used oil acquired from work; my Mini and Capris run just fine for 30,000 miles p/a on the same stuff we used in Transits. At my next job I used whatever 10-40 semi synthetic was in the 200l drum on other Capris, Minis, Avenger, BMW, Legnum, Omega and others. We all did. That was bought solely on whatever the best price was whenever a new one was needed. Even with free oil, I couldn't see any point in changing at the short intervals suggested here; mine got done annually at about 9,000 miles(commuting is expensive!) whether it needed it or not. My Omega got bought oil once, when I was in a hurry and forgot to specify what I wanted. That was a mistake because the 5-30 they supplied made it even less oil tight and noticeably noisier.
Use recycled oil? Sure - it doesn't really wear out, just gets dirty. Recycling it makes perfect sense even before the fact that it's made from a diminishing resource. The only problem with Asda Value oil is that it's more expensive than buying over the counter at a motor factor.
Plugs? I buy NGK for preference which goes back over thirty years to 2-stroke motorbikes. In reality, I've used Motorcraft, Bosch and Champion with no practical difference. I won't buy Denso again as they lasted half the life of other brands in my BMW. Yes, I know that one anecdote like that isn't really proof, but they aren't any cheaper and are easy to avoid.
Filters? I've never looked at the brand on the box, just put the old one in it so they take up less space in the bin.
The only brand I actively won't buy is Goachers beer. That's because it always tastes like yesterday's dishwater strained through my socks.