Tankers - round vs elliptical?

Not sure where else to ask this… my tank experience is focused on milk and I see new trailers in both round and elliptical forms. I assume there’s pros and cons of each shape, but I’m wondering what those are and what leads a company to buy one or the other? My driving has been almost exclusively in round tanks.

I’m inclined to think elliptical is a lower center center of gravity and probably more stable when fully loaded, but partially loaded an elliptical seems like it’d be worse for side to side load shift?