Which glue gives the best strong firm hold?

for plastic I prefer straight elmers white glue.  Holds the strongest, a lot better than the dangerous full of chemicals the solvents have.

Elmer's holds stronger than Tenax or Plast I Weld?  They actually melt the plastic of both matting surfaces creating a solid piece. I just recently fixed a friend's model that had the main gears broken off during shipping. I used Plast I Weld on the gears and they are as strong as before they were snapped off. let it cure over night and will be good as new.

I have a drill that makes a very small hole. In a situation where it doesn't harden, I'll drill through the landing gear and tire and insert a metal rod through to reenforce it.  

I had a similar problem and realized that the glue (Testor's Black ) was simply old, and had probably lost it's strength. A new bottle was the answer.  FYI, for faster joins I also like Tamiya thin glue and Ambroid Proweld. I'm sure Tenax is also a good choice, just haven't used it yet.

Mike