There isn’t a one fits all specification, unfortunately, that is part of the job, to assess what needs sorting and then cater for the degree of wear and tear that lies ahead.
First off, you need to have your problem solving primers onboard, Zinsser is your friend (apart from 123 which is patchy results)
If you want to be really efficient and dont want to spend your whole life flip flopping between brands and bargains that turn out not to be bargains, I would set your stall out with premium paints. The reason being, the cost of materials is a small fraction of the overall cost. If you have to apply an extra coat on a ceiling, that will cost you dear in labour, much dearer and harder on your bottom line than the extra 2 litres of paint. (Dont get into the habit of thinking your time doesnt matter, it is all that matters unless you have infinity pills!)
So if you want to get into a nice long run of jobs that just go as expected, ie redecorating walls and ceilings: prep, fill, sand, spot in filler and 2 coats done, on with the woodwork etc, I would head for acrylic based emulsions. Premium paints.
The UK trade tends to call “premium” paint posh paints, designer paints, over priced marketed paints, in the rest of the world they are called standard good paints that do the job. That’s all it comes down to at the end of the day, using paint that does the job right and as expected.
I can only speak for me, I would just get to know Little Greene / Paint Library for most of my paint, and Mylands seem to have nailed the water based woodwork paint for general decorating. That will give you a benchmark and then go exploring from there into the real high spec Scandinavian paints.
On a budget, ask Holmans about their Manor Coatings range. Their vinyl matt paint is how paint used to be before the accountants fiddled and undermined the quality of UK trade paints. James Graham our Associate Painter and Decorator over in Grantham described it as Leyland price range, but more user friendly. No banding, no patchiness, just apply paint as you were taught, and it works. If you remember oil based eggshell how it used to be, thats how it still is with Manor Coatings.
If you have problematic ceilings that need painting white, carry problem solving primers and use them as a sealer and finish combined.
If your current paints work for you, of course you may have hit on a good combination for your market and forget what I just wrote
All this sort of paint is available by mail order. If you do the maths, you will probably get a shock at the cost of picking up paint yourself.