Looking at buying a portable black tank - suggestions?

a friend had one years back. O the mess when he tried to use it. and then he had to use the quad to tow it to be dumped. and it was not the largest one.
i had thought about getting one for that camp.. but no i would rather pay to have mine pumped out.or dig a deep hole. my black tank cap? but never have filled it up. (small rv).
now fresh water is another thing.