i think during a roto league evans is the more valuebale player since he'll help you in multiple categories. however zach is in a contract year, giving him more motivation. i'd say evans 55 and zach 45 giving evans the nod.
Most formats Evans has PG and SG eligibility which is pretty valuable. As good as Randolph's stats are it's easier to find a PF putting up big rebound and scoring numbers than finding a pg/sg to fill up the whole stat sheet