The First Active E-Saver is a lump sum account, whereas the AIB account is a regular saver with a max deposit of €300 per month - so they're really two totally different things which can't be compared.
I wonder did you mean to say the First Active Regular Saver, which pays a rate of 7.15%??
Anyway, the AIB account is a good option for your monthly savings because the rate is guaranteed to be 3% above ECB until Feb 2009. For a small monthly amount it's the best deal on the market imo. The main drawback is that if you're not already an AIB customer, you have to open a feeder account.
You'd probably also gain by moving your lump sum from the Credit Union to the First Active E-Saver.