As per this question, I bought myself a very nice Ibanez 7 string which I have tuned as A-D-A-D-G-B-E (giving a very nice fat sound which works with the kind of music the band plays)

I didn't think to ask what the string gauges were - but in general I play either Ernie Ball Slinky 9's or 10's on my 6 string guitars.

What should I buy for the 7th string in these two scenarios?