VGBA APK For Android - For one, it's completely free. Rival Visual Boy Advance has an almost identical set of features, but that one will set you back £2.99. GBAoid also has cheats, configurable controls (including for the Xperia Play), top-notch performance, and even the ability to fast-forward boring cutscenes.
Here's our guru guide to download VGBA APK For Android, installing the emulator, and loading up your favourite games.
Note: Pocket Gamer does not condone piracy, and offers this information for entertainment purposes only. Pocket Gamer also takes no responsibility if you follow this guide and manage to bugger up your phone in the process. That's on you, bro.