Not all networks work well in all areas so I'd be careful getting Vodafone without someone in the same area as you confirming they get good coverage. My friend lived in Çalış for several years and her Vodafone internet was pitiful. Poor connection, always breaking up, hard to connect to...
Also so many people over on holiday have Vodafone for the free roaming that you might find summer time there's a higher usage which may mean slower internet for you.
Personally we have always used TTNet without any real issues in 15 years and glad we waited for feedback about these other companies and their super dooper offers and high speed promises before considering a change for the sake of it because I am always seeing people moaning about their internet being down, getting no reply from their offices, being without internet for days, internet is slow, buffering, blah blah blah