base primer for a latex paint?

Doesn't matter. You can put a latex top coat over any type of primer. What you need to be concerned about is what type of surface you're putting the *primer* on. That might make a difference in what type of primer you need.

You don't usually need primer for previously painted wallboard. If new, a latex primer specifically for new wallboard.

Read the label on your your paint can. Since latex may stick poorly to some glossy older painted surfaces, the manufacturer will make note of this and recommend a particular primer. There are also adhesion promoters for old work and difficult substrates that are worth checking out. Take time to go to a real paint store and ask lots of questions. Well worth your time and the prices usually aren't all that much higher than a box store. HTH

Joe

New drywall? Previously painted surfaces?