the butterwoth is the very flat : with no ripples so if u need very flat filter and no amplitude variations then butterworth is the filter u need but this will cost u more area coz it will need more stages to get the same attenuation as chebychev
chebychev : gives ripples in the amplitude but with low order
I think it depends on your specification.
Butterworth has flat respond,linear phase,but poor rejection.Chebychev has good rejection ,but ripple in passband.