Should travellers base in İzmir, Selçuk or Kuşadası for the Aegean sights?
Selçuk keeps Ephesus simple, İzmir gives a bigger-city base, and Kuşadası leans more resort and cruise-adjacent. Pick the base for the trip you are actually taking, not the one that looks central on a map.
Answer
Selçuk is the practical choice when Ephesus is the main reason for stopping: easy access, smaller scale and less time wasted getting to the site. İzmir works better if you want a real city, food, transport links and a less single-purpose base. Kuşadası suits travellers who want resort facilities, sea air and package-style convenience, but it can feel more visitor-facing. None of these bases is universally best. The useful question is what you want the Aegean leg to do: ancient site, city reset, coast break or a clean transfer point.