It seems a bit premature to ditch all acrylics, because of a problem you have with Vallejo, many other modellers use them successfully, including myself - have you stored them properly? I see modellers benches' with racks of paints behind - all open to sunlight.......... I store my paints in a plastic toolbox, in the dark! I also try to store them on their side, although having a load of paints means that's less possible ( unless I buy another toolbox! ). I always add a ball bearing as an agitator to all paints that don't have one. A bag of 4mm stainless steel ball bearings has lasted me the last 5 years. I always shake the bottles for a few minutes, leave them for an hour or so, then give them another shake before use. I always use tap water to thin - the local water is very soft, so no problems with lime scale.
I have a load of different paints, Vallejo, MiG Ammo, Hataka - and my favourite at the moment AK Generation 3 paints. I do have one-off pots of acrylic
Revell, Humbrol, for specific colours.
As my old stocks of paint run out, I'm gradually replacing them with AK3 - I brush & spray with it, and I can't say I have any problems with it, apart from the usual
airbrush hiccups. One of the reasons why I went away from enamels & other solvent based paints was the smell - I live in a flat & don't have any outside areas to spray in, and I don't want that paint odour hanging around for days!
I'll be interested to read about your final decision.................
Dave