As indicated here, there are two companies that make highly break resistant glass:
http://www.theverge.com/2012/6/6/306...phones-tablets
Unfortunately, I say as someone who also has broken a Kindle 3 display, I believe that no eReader yet uses the above mentioned glass.
The only way to find a more reliable eReader, I think, would be if one of the consumer magazines, such as Consumers Reports in the US, or Which? in the UK, has frequency of repair statistics, like they have for cars. However, unless someone can show me wrong, I don't think there is objective information out there as to which eReader is the most durable.