Well most peopel will tell you level >> AA, and they are right. Especially with the new spells you get 71-75.
Now having said that one of your options was solo AA in fire. AA in a group gets based on the highest level person, so AA at 70 in RS sucks with a group assuming there is a 75 in it. Solo in Fire is not bad at 70. If you can pick up an extra 100 AA or so it may be worth it to spend a week soloing in fire.
But if you go there don't stay long, level and the new spells really are better.
Two pieces of advice no matter which way you go.
1) Do the quest for the bracer in Valdehome/Icefall. Turn in 4 pelts.
2) Make sure to get Curse of Sislak and Champion from RS. Those are two spells that are really worth it. There is no upgrade to Champion, and when Rot/Rooting, its good to have 2 magic dots going.