Personally, I vastly prefer autotools, both as a user and developer. When I got to the point I needed some kind of build system, I found autotools much easier to learn than cmake.

As user, I find the experience with autotools to be much nicer as well. For whatever reason, the interface just seems more intuitive. I mean, ./configure --help will tell you basically all you need to know. An underappreciated bonus is that you don't have to install more stuff just to __build__ some program you might not even want. I've run into more than one project that required a specific version of cmake, which as luck would have it, was not the version packaged with my distro. This leaves you either building another cmake first or finding a tool/library that isn't so persnickety.

Given the choice between trying a project that uses CMake or or autools, I'll choose the autotools based project every time.