I scratch built an engine and stuff kept snapping off. I tried different stuff and they all seemed the same. Rich at Korber models suggested I try the Gorilla super glue for assembling one of his buildings I had purchased. I used that on my scratch build and nothing broke off any more. It is all plastic.
I imagine each response here will get whatever one has best results with. I didn't like regular superglue because it gets brittle and stuff will snap off over time. I tried industrial plastic glue that will kill you with it's vapors, and stuff still snapped off.