I like custom bases
I think they look nice all painted up, but at the same time I own very few of them and prefer to make my own because I'm cheap. Something like 15 years ago I bought a tub of woodland scenics rough and course black railroad ballast, I mixed them together and I've been using that ever since. I don't think it's even half gone yet.
Maybe once I get started sculpting I'll try and put together some toppers as a separate little pack and see about making them in resin and see if folks like em... rather than including them in with the minis that could drive up the prices.