Whats the best chain and spocket combo

[sledhead69]

I have a 2006 yz 450f i need a new rear sprocket and have just decided to upgrade everything i do a lot of cross country riding with atvs, jumping and every onces and awhile i get on the track i want something that gonna last as the original got ate up pretty fast what is everyone preferences

 

[Bodge]

Ive had good results w/ primary drive steel sprockets and primary drive x-ring chains.