This really comes down to how durable you would like your sink to be and if you want it in a color or not. I would never recommend a porcelain sink because they are very hard to keep from getting scratched, which only makes them look old right away.
The right answer is likely a Stainless Steel or Granite/Quartz composite. They are the most likely to retain their new look the longest and are easy to care for. They are also in an affordable price range. Other materials like copper or fireclay are available especially if you are looking for a farmhouse sink, which would typically be porcelain. However, for most people they want an under-mount sink, and I would highly recommend Granite/Quart composite first and Stainless Steel second.