Graduate Diploma in New Zealand or Masters in UK?

I am Asif from Bangladesh. I was offered a place at Auckland University of Technology (AUT) in Graduate Diploma in Business course. I submitted my file for getting visa and in the mean time I applied to some UK Universities and got Offer letter from University of Salford for MSc in Marketing and from University of Dundee for MSc in International Business and Marketing (with 1500 pound scholarship in both). After that I withdraw my student file from New Zealand emby because I think doing masters is better than doing a simple graduate diploma. I was on the edge of getting New Zealand student visa but I consider my education prospects and ignored it. But now I am thinking..have I made a good decision or not?