Stick to the plastic ones. Despite lots of effort over many years, no one has come up with anything that matches the performance of the plastic ones. The lowest friction is with the plastic ones, anything else raises friction and compromises handling.
Make sure you lubricate the kingpin with enough silicon fluid to prevent the dirt getting in - a smear will do the trick - and they will last a long time. If you don't like damping on your front pins then use a 3000wt oil. Clean out everything thoroughly and re-lube after every meeting to maintain the performance of the suspension.
The fit in the socket can be fixed with a smear of superglue on a cotton bud if too loose, and if the kingpin or socket fit is too tight, select another ball. Metal ones will not fix those fit issues. HTH
