I am thinking

I am thinking what I will buy a dictionary or won't.
At times like this, Which shold I select English-Japanese dictionary or Japanese-English one?
Do I need to buy it in the first place?
But I will stay in New Zealand for over a month, therefore  I feel to need it maybe.
I have a smartphone so I feel like I don't need it.
If I buy one, which one shold I select? I'm thinking...