I'm wondering what the best EFA is? I usually use a standard unbranded one from Holland and Barrett.
The one you're lacking.
Any EFA that you're lacking will have the greatest effect once you increase its dosage.
With that said, a fishoil supplement should cover your bases. Get the rest of them from food (butter, various oils etc)
Afaik, there are only two essential EFAs, n-3(alpha-linolenic acid), and n-6(linoleic acid). So these are the only essential fatty acids.