Do I want an “equal slot ribber”?

It depends.  Same slot ribber dials allow you to do all functions of a half slot ribber and additional options such as 2×2 ribbing.  Some people prefer them for their flexibility and the ability to do half pitch ribbing. Others find them harder to use (because there are more slots, and can be harder to line up), and prefer half slot ribbers. In the end, it comes down to a combination of personal preference, and what you want to do with your machine.