Even though i haven't done the quest or gotten the staff, I'd think the ancient staff is much better. Here is why:
1) Ancient Staff allows casting of multiple enemy hitting spells such as ICE BARRAGE (lvl 94 magic, 30 max for everyone in hit area and 15 sec freeze)
2) Each spell has its distinct effect. (e.g. ice freezes, blood restores hp)
3) You can take out entire clans with this (cast blood barrage and sit back)
These spells are a bit expensive but are the BEST spells out there. Much better than the wave spells and ice barrage has the same max hit as the arena spells with multitarget and 15 sec freeze. Just check the desert treasure quest guide. Don't have the link but just look it up under quest guides at the main page,
http://www.rsbandb.com