Reply to thread

You only specified delay and load but you must also specify BW which determines  N poles.

τg(ω)=−dθ(ω)/dω = group delay

What BW do you want? or risetime?

The Bessel filter has better shaping factor, flatter phase delay, and flatter group delay than a Gaussian of the same order, although the Gaussian has lower time delay and zero overshoot.  The Chebyshev filter is best for rejecting side lobes with steep skirts.