32GB gives you double the storage for Apps, pictures, and other media contents. If you plan on storing a lot of data, the 32GB would be ideal. You can get a 16GB and add additional media through a memory card if you'd like later. And you can add memory to either model.
But if you know you're going to be a heavy user and you use a lot of data, you may want to consider the bigger memory option initially.
If you have further questions, you might also reach out to a Best Buy salesperson for more information, and they would be able to assist you further based on your needs.
Thanks for your interest in Samsung products.
--Mr.Samsung