The ‘right’ filter is the design that does what you want it to do considering your data.
With FIR filters, the filter length increases significantly with shorter transition regions (steeper rolloffs). For example, if you have a short data vector, the third design (passband frequency 0.49π and stopband frequency 0.5π) may be too long to work with your data.
Shorter filters are more efficient, so if the filters you posted all give the same essential performance (as I expect they would), I would use the first design, with the passband frequency 0.45π and stopband frequency 0.5π.
Best Answer