It depends entirely on your needs. Mandarin (Simplified) and Mandarin (Traditional) have the same pronunciation. The difference lies in their writing systems, so it depends on where you intend to use Mandarin. If you plan to visit China and Singapore, Mandarin (Simplified) is the preferable option. However, if you intend to visit Taiwan or Hong Kong, Mandarin (Traditional) would be more suitable. You can see the differences between Simplified and Traditional Mandarin with our post here.