It really depends on your users requirements.
I recently started a project in the Google Maps API, where I overlaid some services from ArcGIS Server and had some basic queries going on. I wanted to use Google, so that I could legally incorporate their Streetview/Geocoding/Traffic APIs into my map. As this would be a public facing application, I also thought it might be more familiar to the end-user.
As you would expect, this API is continuously updated to match the functionality that is dished out with each new version of ArcGIS Server.
You mention that your just displaying your AGS services on a map, and just need to provide pop-ups. If this is really all the users need, then you can pick from plenty of APIs to do this e.g. OpenLayers, Leaflet, Google Maps, etc.
However, perhaps your users only need the basics for now, but perhaps as they begin to use the application, they start to want things that only the Esri JS API offers? On the flip-side, perhaps they want things that they see in the Google Maps API?
I find the latest version of the Esri JS API easy to work with. Dojo has definitely improved significantly (API built on this) and you can easily make use of other frameworks like JQuery alongside the Esri API. But then I am also a fan of the Google Maps API, mainly because of the additional services you can leverage, but also some of the cool stuff within the Maps API, like styled maps and radar search.
Short answer - depends on who the users are and what they need.