Best Ereader for getting English language books in the Netherlands

Dear All,
Unlike the usual posts, my problem is how to get English language books in the Netherlands onto an Ereader (Eink not LCD). The cheaper readers available here with integrated online book stores (Oyo for example from Selexyz) only read epub and exclude the 100,000 books available on mobipocket. The kindle can only be imported and not bought here. The Sonys use their own online book store but with a reduced selection compared to Amazon. Does anyone know the best Ereader when it comes to having easy access/payment/wide selection of books? Another additional problem is that I have a macbook and dont use Windows which I believe you need for the Sonys.
Thanks