Actually not a Stupid question... And one that's been debated and never succinctly answered.
Because you use the term AAS, then you throw out a host of options that are better then Anabolics. So, since you're looking at AAS only, then mostly the Orals are the best; but, in terms of fat loss with low sides. If sides aren't a factor and overall performance is the deciding factor then; naturally, Tren is the best. However, it's not really recommended for most women.
Hands down the best compound for fat loss (fat loss as only criteria) is DNP
Second option would be T3/Clen cycle. Less fat loss then DNP, but sides aren't as severe. However, they are present.
This is only based on your request ..for fat loss only. Not other considerations which go hand in hand with consuming exogenous compounds