Chris... in theory the most forgiving arrow is gonna be the most well tuned arrow. Weight shouldn't make a difference.
A perfectly tuned arrow/bow combo should give you consistent good flight, but that really only applies to the relationship between the two AFTER the arrow is in motion.
A lot can happen at the moment of release that the arrow has to recover from before it can go through "normal" paradox. Torquing the bow, torquing the arrow, torquing the string all affect the way the arrow comes away from the arrow rest.
For that reason I'm an advocate of a very soft rest. It helps absorb some of the bad stuff we do at the moment of release and makes the bow more forgiving.
As an example, a plain piece of leather for a rest is not very forgiving. Putting a piece of match stick under the leather where it contacts the arrow makes it more forgiving.
A piece of Bear Hair type rest or fuzzy velcro is even softer and even more forgiving.
The most forgiving of all would be an elevated rest with some type of adjustable cushion plunger as the arrow plate.
Lots of choices in this sport.