one camera or several?

I'm pretty new to Unity.. I'm building a game that will have several cameras, one of which is randomly selected at the start of the attack scene and rotate/move around the player. My question is whether it is better practice to use one camera and move it wherever I need whenever I need and then pan it, or is it better to put several cameras in the scene and switch between them? As far as time to build, I'm sure it'd be easier to use several cameras but I'm not sure how this will affect FPS, etc.