Below is the erraser that I use. You should be able to find them at some stationary stores at Malaysia.
a) & b): I love to use these both erraser to carve. They have the same texture and they are medium hard and easy to carve.
c): I never use before. So no comment on this. I guess should be the same as b)
d): Similar texture compare to a) & b), just a bit harder,with a larger width of erraser for larger width of stamps.
e): Medium hard erraser
f): Soft erraser. Easy to cut but too soft, sometimes will miss cut those fine lines.
To me: softer erraser is more easy to carve. Because you don't need too much enegry to carve them. It is not good in carving for fine lines. I prefer medium hard erraser. I don't use those branded erraser. I find cheap errasers are so suitable for stamp carving. I recomend to try on a) or b) erraser for beginners.