Who would be some active or can even be very recently retired/deceased mobsters who you think have seen the most things throughout their criminal careers, not necessarily the most successful or richest just ones who've been around for a lot. A few that come to mind

Albert gallo...to be around during both Colombo wars with his brothers and then switch families to still be active today.

Mario gigante...retired but I'm sure he has seen and done so much.

This is just a start I'm sure there are tons more.