There is better and worse, good and bad within and between cultures. The culture in which you were raised will certainly affect your ultimate judgment, but there are (or should be) cross-cultural universals and logic and rationalism can be applied to find them. They (logic/rationalism) can also be applied to determine beneficial or counter-productive, good or bad, and better or worse as well. This doesn't mean that everyone will reach the same conclusions in the same way, but a general consensus of fair minded, rational and intelligent people is possible.
I personally abhor relativism of almost every sort. Its excuses and encourages abuse and barbarity. There is not rational justification for institutionalized discrimination and bigotry if one wants to be considered a just and righteous society. 'Its their culture' is not an excuse for rampant repression and corruption. These are not the signs of a different culture. These are the signs of an inferior, and if it gets too extreme, a barbaric culture.
Free expression, civil rights, general equality under the law, the establishment and codification of laws, representative government, etc are superior cultural values to their direct alternatives.