To give a contrary opinion to Macro’s Zend\Db has it’s place. It’s an excellent tool for rapid development when you know that you have certain constraints (e.g. short lived projects). It’s an excellent intermediate step if you’re trying to move away from concatenated strings run directly against pdo (or even worse mysql_). It’s an excellent choice if you are writing a web database and all of your operations are crud-like.
I’ll leave other’s to argue if you should be designing crud-like systems in 2018, but I want to make sure that this thread’s final message isn’t “never use Zend\Db, always use Doctrine”. Like every tool it’s horses for courses, and I’ve personally used and scaled Zend\Db elegantly and in a maintainable way.
Be wary of anyone who makes sweeping statements like “Don’t use this well maintained and fully mature tested library, use this one instead”.