Charge pumps are favored for ability to integrate, when the
current is reasonably low and the voltage multiplication is
not huge. I have built 3V:75V charge pumps on chip (some
decoupling external) on specialty technologies but generally
you'd be limited to your available device breakdowns on a
normal junction isolated technology.
A boost converter doesn't limit you if your power switch is
external, but a highly integrated internal boost converter
would want either not-so-common devices (HV LDMOS, HV
Schottky) or some significant design elaborateness and
HV PMOS, or both. And the inductor, fuggedaboudit. That
slug of iron is gonna need its own bedroom.