Of course, the location of your property is entirely down to personal choice, but below are a few facts which might help with your decision. Don't forget that a property might be ideal as a holiday home, but if you plan to live in Turkey, now or in the future, there may be different factors you need to consider.
Kalkan is 30 minutes closer to Dalaman Airport (journey by car is approximately 1.5 - 2 hours). However, Kaş is served by both Dalaman (just over 2 hours) and Antalya (just under 3 hours). Antalya has a wider choice of international charter flights during the winter season.
Kaş is the local administration centre for the immediate region and has more choice of general shops, banks and other services. It has an indigenous population of around 8,000 people, so many shops and restaurants etc remain open during the winter season. It is also home to the area's only secondary schools and has its own small hospital.
Kalkan has a better choice of restaurants, though Kaş is catching up fast!
If you are planning to move to Turkey permanently, you will find that Kaş has a much larger all-year-round foreign population, which is again reflected in the number of shops, restaurants and services staying open during the winter season.
Kalkan is very popular with British holidaymakers, while visitors to Kaş are from more varied locations and it continues to be a favourite destination for holidaying Turks.
The cost of both eating out and everyday groceries tends to be slightly lower in Kaş than in Kalkan.
Kaş has no sandy beaches, but it does have a number of free beach clubs with sunbathing/swimming platforms, as well as easy access to the sand/pebble beaches across the bay at Liman Ağzı. Kalkan has its own small beach and is closer to the sandy beaches at Patara and Kaputaş.
Both towns have a good selection of properties, from small apartments to large villas and everything in between. Prices are generally higher in Kalkan than in Kaş, though the difference is becoming less marked.
Kaş or Kalkan?