depending on how many adds you haven't in cc imo. the less adds, the more benefit from barrage. if you're pulling all 8 adds, arcane explosion will clearly go ahead (at least with mastery focus, dunno about haste).
for my arcane mage with mastery focus, we cc 3 adds:
i just stand in my rune, use living bomb+fireblast w/ glyph, use flamestrike on cd, and spam arcane explosion. when i hvae enogh stacks i throw in barrage as well.
if the health of the mobs has to be adapted (trappers to high or sth) i use normal rotation with cleaving barrage.
spamming explosion is probably the easiest way, and it pulls quite decent dps too.
best you try both, explo spam and 6 stacks/clearing, and use whatever you like best :>