Having looked at this recently, if you want to go down the air compressor route, have a look at the Gentilin options. For example, the CSK240/24 is rated for spraying, and is only 67db from
Gentilin Air Compressors at Sprayman UK - SpraymanUK. It's less about the size of the tank and more about the rating of the compressor itself and whether it can keep up with the air demand requirements.
If you don't want to go down the air compressor route, I liked the look of the Graco GX FF Airless sprayer
Graco GX FF Airless sprayer | Spray Plant as it's the best middle ground between spraying cabinets and spraying a room. It can do both if you change tips. Haven't hit the button yet, but that's the one I settled on.
Sprayman also do the GX21FF
Graco GX21FF - SpraymanUK that can do both too but is higher rated for doing rooms on a regular basis. The smaller pipe diameter and hopper mean you use much less paint (you'll loose 100-150ml from memory).
The Graco Ultra hand held only does a 150l before requiring a new turbine (£150-200).
Or, if you decide to step away from spraying, I like the Two Fussy Blokes 4" smooth roller - gives a decent spray-like finish.