1. Erdogan’s opponents can’t guarantee Turkey’s accession to the EU
EU already declared that if Turkey moves to such dictatorial regime, they won't accept Turkey as a member.
2. The opposition doesn’t have a plan to improve Turkey’s economy
During the last Turkish lira lost tremendous value against Euro and Dollar.
Inflation and unemployment breaking new records every new month.
3. Erdogan is trusted to improve the deteriorating security situation
When AKP with Erdoğan come to power back in 2002, they invented a new slogan..."Zero Terror."
In 2002 there indeed no terror thanks to countries non-stop effort intensified effort which started back in 1993. Erdoğan stopped the operation and gave a breatking room for PKK. PKK regained it's strength in 2008 and begin terror attacks. Instead of warring against Terror, he tried to deal with the terrorists ( " Peace Process " )...which enabled PKK to recruit more, bolster it's defenses, acquiring new weapons and tactics, forming "urban" and "county" terrorists.
In 2015 PKK again begin it's terror attacks and it was a whole new level that Turkey had never experiences before. We even had to use tanks inside towns.... unprecedented.
His relations with Gülenists dating back to 2002, resulted with Gülenists to infltrate army, state organs and jurisdiction which resulted with July 15 coup and caused more than 200 citizens' lives.
4. Erdogan already has a proven track record in Syria
Meddling into a neighbor state's internal affairs, stirring the civil war, blow back to Turkey resulting many ISIS attacks in Turkey thus dragging into Syrian swamp where we lost several soldiers.
5. Voters are more interested in a ‘strong Turkey’ than a ‘democratic Turkey’
Just a claim non different than me claiming "Sun's color is purple."
We shall see on Sunday, but after all the examples i gave above, you should be crazy to believe Turkey would get stronger with Erdoğan at helm, it's only deteriorate even more.