If you are in the middle ages between 25-40, best to travel in May, June.
If you are looking for ski resorts, December (end of), January, and February.
If you are above 40+, the best time travel is March, April.
If you are a family with kids, it is best to travel in August, September, October.
If you are a couple, Turkey is yours but the swimming period, May, June, July, August, September. Other periods are a bit cold and in Autumn mood.