Ask HN: what is the best way to seat together?

In a software development company we have developers, testers, designers, etc. There are two ways to sit together: 1. By functional teams. Several developers sit together and share knowledge and information. Several designers sit together, etc. 2. By cross-functional teams. These teams consist of 6-10 people (dev, testers, designers) that are focused on a specific feature or module. It may server the goal well, but what about learning? So what do you think? What option you think is best?