Germany/Ireland vs. Greece/Turkey: two totally different experiences.
During the summer, the southern European option takes places in a hot, arid climate. You're going to sweat a lot want to jump in the crystal clear blue waters. The food is amazing and sure you're going to see ancient stuff. The people tend to be friendly towards tourists while also having a southern European attitude towards prices: one rate for tourists, one for locals, and room for haggling. Behind your back they may also curse the day you were born for being a Westerner, etc. But you'll never know this.
The northern European option will be greener, cooler, and a little more humid with greater chance of rain showers. Ireland (Dublin/Galway) is full of fun-loving people, green rolling hills, music, etc. What you see is what you get in regards to pricing and interaction. In Germany, you enter the crossroads of the 20th Century for better or worse. You have tons of options from focusing your vacation on beer to fast cars to battlefields to the Holocaust and everything in between. You have museums and cultural activities that cater to every interest. And in both northern cases, you can expect the food to be of the meat and potatoes variety with less spice and flare compared to the south.
Flip a coin?