Why filter through hardware?
You want to at least use hardware for your anti-aliasing filter.

This means filtering out signals and noise above the Nyquist rate (1/2 of your sampling rate). You have to do this in hardware because after sampling, interference or noise in the alias bands won't be distinguishable from the signal in your desired band.

Whatever other filtering you want to do will likely be easier if you can use more oversampling. At which point you will have a trade-off: Does increasing oversampling cost you more power or does using analog filters?