Got my 10 year old air brush (not used in 9 of those 10 years!) cleaned up and pumping alcohol out. But the real surprise was the paint. My Polyscale is also about 9 years old and had been stored in hot & cold environments. Lots of shaking, few drops of alcohol and walla. I’ll be painting track railroad tie brown - Yahoo!
In my opinion, there isn’t one, or at least one worthy of being the replacement.
I use Pollyscale for almost everything, but am running out of black and white, probably because they were the colours most-used. And while I do a lot of airbrushing, I find it much easier to paint rail using a 1/2" chisel-type brush, and also found it to be very relaxing. Brush-painting turnouts is a breeze.
You can paint anytime you feel like it, even if you have only 5 or 10 minutes available - rinse out the brush and cap the paint, then go for supper, with no need for masking or clean-up, and much easier to do the normally-unseen side of the rails on an around-the-room layout.
That’s an important consideration if you take photos with your camera on-layout and facing out towards the aisle.
Color matching can be done. Microscale made a chart of the polly scale colors and who makes a matching color. So at least you can match the colors as the paint runs out