to be honest i did yaks with knives but as of recent it has been very crowded so I would rather do fire giants.
and as stated above getting chins is really the way to go at 85+ range.
also if you have void with void deflector you can substitute the chest area with d'hide (or armdyl, Pernix?) and seriously increase your accuracy. I personally chinned at ape atoll dung with the skeletal monkies. (the deflector can replace any void item but the headpiece)
chinned 97-99 and it's the fastest xp ever. umm but do bring ring of life... it saved me 2 times lol (of the 4 times i chinned or such)