When I review engines I usually test 4 different brands of plug (various). I have found quite a bit of difference (in terms of top RPM, idle, and transition response) especially bewteen brands like Fox, OS and others.

Personally, In most engines I like the OS #8 and A3, the K&B 1L, the Hangar 9 super plugs and the Tower Hobbies "OS#8 clones"... I find myself using OS #8's in most of my engines. The OS F in 4 strokes still seems to be the longest lasting and without issue.

Just my experience/opinion.

AJC