My suggestion is similar to Eileen's -- there are many options to choose from, so it does depend on your musical interests. I perform with my T5, so having good electric piano sounds is nice. The Vintage Keys pack provides this. But if you're not interested in, or in need of that, then other packs may work better. I have all the Yamaha developed packs for the T5, and I can say they consistently have done a good job with the quality. And I also agree that getting the 2GB expansion pack is worth it. Once you start buying expansion packs, the memory usage goes fast and you will wish you had more.