I use the KME broadhead sharpener and it is roughly 25 degrees but that depends on the width of the head and how deep you put it in the clamp.Whatever angle they come out,25,26 degrees or so.
It may however depend on the particular head and the hardness of steel.A double bevel head,ground at 25 degrees has a total angle of 50 degrees.So 25 degrees is a very sharp angle and some steels may not be tough enough to support it.
I suspect most makers have figured out the best angles for their heads and it may be best to follow that if your sharpener can adjust.
New Grizzlies should be close to 25 as would Tuffheads and I think,Abowyer.I'm not sure about other single bevels.Old Grizzlies were 30.