The answer should partly depend on the construction of the boots, leather type, finish, etc. So many ways to skin a variety of cats. I'm finding myself using a lot less heavy waxes and greases while using more silicone type creams and sprays. Leather seems to remain sturdier and cleaner without the dirt-attraction characteristics of the sticky applications.
Should check with your boot manufacturer. Kenetrek says to use theirs. It doesnt cost more than others so I might as well use what they recommend. Some warranties make you use what they recommend.