What is the best to use for arrows shot from a longbow? I want to order a fletching jig but im not sure if I should get a straight jig or helical

Archery is a give and take world. The more feather twist, the more stable in flight, but you'll give up a little speed and cast, but IMO, so slight you'll never notice it with traditional equipment.

I prefer helical for 3D shooting and especially for hunting. Helps stabilize my arrow sooner, if windy or I have a bad release.  I shoot aluminum arrows and bare shaft test to achieve the most accurate flying arrow.

I believe that they will all do the job. Over the last 40yrs. I have tried each way and all have performed as expected. However since I shoot Hill type longbows I have found that because of my grip, very close to shelf I can get feather burn on my left index finger knuckle with either helical. So I went back to straight offset left to allieviate this. You could simply buy all 3 clamps and answer your own question over time.

For hunting?  Or target shooting?

I wouldn't shoot broadheads without helical.  With offset fletch it might go straight or it might corkscrew - depending on how it came off the bow, and what the winds are.

I shoot straight off set RH & have never had any flight issues, did try my RH helical clamp on my Bitz & really didn't see any advantage/disadvantage to it so I stuck with what has worked for me for over 25+ years.

My vote goes for helical

Left helical or left offset for RH archer for a longbow.

I find that helical gives better shaft contact over the length of the fletching

I like Helical

The thought of left for a right handed archer is an individual thing.
Some people use that for clearance issues but many don't see any difference whatsoever. The actual wing being used doesn't make a bit of difference for left or right hand. Just be sure the correct clamp and offset is being used for the wing.

Guy

I shoot left hand helical out of my selfbow.  Feather burn on my finger aint too bad once you get used to it.

I like helical and I shoot both LW & RW helical depending on the which feather I'm fletching.

i have shot both cant tell any differance i like straight with a 2 degree offset has been working for me so far

2 degree offset works for me too