What is the best glue to attach for plastic to plastic?

E6000 works well on most surfaces, and JB Weld works great on plastic to plastic

E6000 comes in white and clear. I like the clear as it does not show once dried.

Krazy Glue or Gorilla Glue works great for plastics.

I use two kinds, E6000 or clear Gorilla glue. CraZart also makes a pretty good glue. For permanent use, I would use one of the first two mentioned.

Glue 6000 it holds nearly everything.

Epoxy.