Scale Coat II paint remover, available in most hobby shops (usually in the train section). It strips paint in ten minutes and it works on every type of paint. Yes, its caustic and you need protection, but its not as bad as some products I've tried. You can keep it in a sealed tupperware container and it will last forever, replacing only what gets washed away as you're cleaning models. Its the only stripper I use anymore. It will wreak havoc on resin unless you're very careful about time.