We sometimes become confused about what material we should buy. Both of them have their pros and cons.
Stainless steel material can be used in almost all the ingredients. But these are not appropriate for measuring liquid ingredients as we cannot see through them.
Considering the plastic cups, it can be used to measure liquid ingredients as well. But the con of this side is, they cannot be easily washed as they produce a hazy texture over the surface after use.
Stainless steel cups are easy to maintain, durable and stays longer. While plastic cups wear off easily after time, so, overall, we can find that stainless steel cups are slightly better than the plastic ones.