spark plug ?
Generic question needs a generic answer, so I'll do it.
You really can't go wrong with NGK plugs of the correct heat range for your engine build.
Yes, this is my oppinion, but considering that NGK makes plugs for a ton of the other brands anyway and I have always had good luck with them I trust thier quality.
I don't mean that I just never had a problem with them, but have had problems with other plugs that changing to NGK fixed.
There. :-)