I've used Millions of erasers over the course of my art career but I've finally whittled my choices down to 2 kinds.

A) Kneaded Eraser:
This eraser usually comes as a plain Grey or Blue square. Once you open it from it's wrapping you start working it like silly putty. Squeezing it into a Ball...pulling it into a ribbon..folding it, squishing it..Kneading it, really. What's the purpose? Well, you can squeeze it down into a fine point and erase lines in hard to reach places without disturbing the pencil lines around it. Another handy feature is that it doesn't completly erase lines...If you just dab the eraser over the lines you can lighten them up for inking.
Back to Materials B) White Nylon Eraser:
This style is the best eraser I have ever used for completly removing pencil lines without destroying your inks or gouging your paper. It also has a low "debris" factor. Debris is that rubb off you get from your eraser.