Nick

48 khz will not improve the quality AT ALL

Key thing for quality is bit length so record 24 bit rather than 16

There is an argument that says 96 khz is better than 44,1 but, no insult intended, you will not hear a difference with the equipment you are using.

24bit 44.1 will be fine and is the standard for nearly all commercial recording other than classical which might often be 24 bit 96khz - but they will be using very posh mics and pre amps.