I have several portals, although with the way hospital systems are merging around here, I’ll probably be on just MyChart eventually for hospital-affiliated doctors. My PCP has her own portal, my dermatologist and urologist each have portals linked to their large practice groups - none of these doctors are linked to a single hospital system.
My D works in the medical records/electronic systems space. She has one personal doctor who uses a particular portal that drives her nuts … she so wants to fix what doesn’t work!