As far as liquids or gases are concerned, rocket fuel is the best, it is a solid, but it requires a lot of gas processing, and to make a lot of it, it takes a notable infrastructure, even liquid plastic and liquid resin, the best recipes to produce them. in larger quantities, they are very complex. The other gases, I do not know, using Bob and Angel's together, the two mods combine to form many products, but I honestly do not know the angel alone what can be done. Used together with Bob, you might be interested in putting difficult metals like tungsten and titanium, silver and gold. If you then also put the bob modules, then the complexity increases even more