That I can't really tell. Android devices come in a variety of (native) resolutions. Whatever looks good on one device, might look bad on another. You need to check several devices. The Android emulator allows to configure screen size and resolution (not sure if 100% freely, but you have several options), so you can check there as well.
For our project we historically decided for 1024x600. That looks good on a variety of devices, independent of their native resolution (wmelite will scale the picture to fullscreen, keeping only the acpect ratio - thus a ratio of around 16:9 should be used to keep the black bars at the side of the screen small).
More important was the use of the "pixelperfect" rendering option in the "settings.xml", as we could not afford inaccuracies of graphics when they were all individually scaled when being drawn. That option is on one hand very memory intensive (you need a back buffer of your graphics in original resolution and depth in memory additionally), but avoids scaling artifacts between individual graphics. It depends on how you arrange your graphics, whether you actually need this option. It should be kept off if not necessary.
