can't say yet, bro, haven't tried enough kinds.  Maybe an elm with 2" wide limbs?
The rune-inlaid holmie i made last month has limbs over 1.5" wide, and very thick, around 1/2" anyway, if not more, but it is still feather light.  It was 62" long i think.  This one is 5" shorter, the limbs are 1.5" wide max, and very thin, hardly more than 1/4".   Both have taken a fair amount of set.  Maybe yew will still be the prizewinner, if sinew backed...Even with the string follow, these holmies shoot fast...with no string follow....