Samsung Wave 3 runs Bada OS (By Samsung) so not much good than Android, Samsung Galaxy W is a good phone that runs Android almost the same as Wave 3 but it has smaller screen with 3.7inch TFT while Wave 3 has 4.0 Super AMOLED screen.
And for Samsung Galaxy Ace is not recommended. Because the processor is bad and lagging and does not support adobe flash player Hmm but if your mom is standard user Galaxy Ace is okay if she don't install much apps in it

Hope this help