I know this is a common question. But I have always liked feathers. What the advantages and disadvantages of both? Also.... straight or helical?

Feathers......
Lighter, but more drag stabilizes arrow faster. Need protection from the weather, but shot to shot more durable. Faster initially due to being lighter, but A touch bit more drop at long ranges due to the extra drag. Increases with a hard helical but fine for most practical hunting distances. More forgiving to incidental contact.
Vanes......
Heavier but weather proof.....also a bit quieter if you have the right ones.(And they aren't ripped) More downrange velocity at longer ranges.

I like at least a few degrees (3-4)of offset on either vanes or feathers and I shoot mechanical heads.....if I was shooting fixed blade heads I would put a good helical on either feathers or vanes to stabilize the arrow flight better.

I really like feathers but they do require some extra care. Whatever arrow I choose for hunting season this year will have feathers in a moderate helical.

What Matt said

thanks for the info guys. feathers sound good to me too, and I like the way they look.