I wouldn't say liquid is "better". The neutrinos don't care from a cross section standpoint.
Uniformity of the light field is going to be different, but that is not my sub-domain.
A liquid you control (and can densely instrument) is going to be a much easier to characterize detector than large volumes of natural material
Wouldn't the higher density of liquid water be an advantage?
A liquid you control (and can densely instrument) is going to be a much easier to characterize detector than large volumes of natural material