I've mostly taken database abstraction for granted since I started at Zend. We had a decent abstraction layer in ZF1, and improved it for ZF2. There were a lot quirks to it — you really had to dive in and look at the various SQL abstraction classes to understand how to do more complex stuff — but it worked, and was always right there and available in the projects I worked on.

In the last couple of years, though, we came to the realization in the Laminas Project that we didn't really have anybody with the expertise or time to maintain it. We've marked it security-only twice now, and while we've managed to keep it updated to each new PHP version, it's becoming harder and harder, and whenever there's a CI issue, it's anybody's guess as to whether or not we'll be able to get it resolved.

My alternatives have been straight PDO, or Doctrine DBAL, with the latter being my preference.

I'm a big proponent of object oriented programming. OOP done right helps ease code maintenance and enables code re-use.

Starting in PHP, OOP enthusiasts got a whole bunch of new tools, and new tools keep coming into the language for us with each minor release. One feature that has had a huge impact on frameworks and libraries has been available since the earliest PHP 5 versions: visibility.