You can never have too much RAM, get as much as you can afford. Certain apps will only use internal memory (BBC iPlayer downloads being one, irritatingly) so the more you have the better.
I've just upgraded from an 8Gb Android to a 16Gb version, and also have a 64Gb SD card in it, mainly for music. The 8Gb one was always close to full on the internal memory even with as many apps as possible shifted to SD.