This is difficult question to answer without knowing the full extent of your needs. Essentially these are two very different platforms. For simple structured, repeating content WordPress meets the need very well on many levels. The level of market saturation alone makes WordPress a good choice for sites that are basic.
AEM is an enterprise content and marketing platform with an architecture to handle complex and wide publishing and distribution workflows. The authoring experience is fundamentally different in terms of allow unstructured content to live natively in the architecture and authoring experience. WordPress and Drupal have to force content structure due to the nature of DB and fixed templates. Marketing content is usually not bounded by structure so you end up doing complex IT work to "spoof" the freedom marketing usually needs.
AEM asset management and configuration is also a differentiator. Everything is content and can be mashed up in a seamless UI for authors. I have not seen a plugin combination that does this well in WP and when an attempt is made, one is usually subjected to the diversity of vendor limitations. I've built CMS solutions in WP and one is usually walking a tightrope of many plugins and a constant battle to overcome the natural publishing flow in WP.
The question is valid if you are starting to look at platforms, but when use both systems to do enterprise work you see the tradeoffs quickly. My advice is always understand your authoring and business needs, narrow it down to a handful of prime directives and then watch for platform alignment or dissonance. If you find yourself saying "override" more then "extend" then you are probably looking in the wrong direction.
