Hah...paint. Something I've become very familiar with recently. I've used a number of paints recently. We've got:
Dulux Supermatt on the ceilings - good watered down as a mist coat on new plaster but also very good on ceilings. It dries opaque, covers well, is very matt and touches up well too. No sheen at all so very forgiving and will hide many imperfections. Pretty much no durability or wipeability but hey, it's for a ceiling!
Earthborn clay paint in our living/dining room. Eco paint but our main reason for choosing it was colour choice. I wouldn't use it again to be honest. Very matt and covers very well in one coat but not durable at all. It's a breathable paint so will absorb moisture and let it out again. Fine for water - in fact it might not be a terrible choice for a bathroom as it wonto streaky - but any other liquids will stain it. Only very lightly wipe able, not great for touching up either.
Little Greeene Intelligent Matt - if you like the matt look then I highly recommend this paint but it's not cheap. We have it in our hall/landing/stairs and while it's not indestructible (if you want someone super touch then look towards Dulux Diamond Matt) but it wipes clean very well. If you scrub too hard you will affect the finish and it doesn't touch up brilliantly but not badly either. But I've wiped all sorts of marks off it including red pen. Excellent paint, but not the easiest to paint with.
Valpar premium matt in my daughters bedroom. B&Q sell it and they can mix any colour. Matt with the slightest sheen as its scrubbable paint. Yet to be fully put to the test but it's a nice finish. Was almost put off by terrible online reviews but it looked great after two coats. First coat was terribly patchy over mist coated plaster but second coat was almost perfect. You need to be careful not to over roll it. Get it on, lay it off then leave it.
So...if you want a normal matt look, the Valspar stuff is worth a try and you probably can't go wrong with Dulux either. If you want to try one of the posher paints I'm very happy with the Little Greene paint. We used their eggshell too for the woodwork.