Best device for longest security update support period/lifecycle?

[dexfour]

I am disappointed with Xperia Z3 Compact's 18 months life for security updates. This period starts upon its release. So my device received only for 13 months after I purchased it.

Please suggest me a brand/device with a satisfying security update support period. I don't want to use a smartphone/device with known security vulnerabilities. This is my top priority.

I live in Turkey. Google devices are sadly not sold here.

 

[chanchan05]

Samsung supports for 3 years on flagship devices (S and Note series) starting from time of release, but this may vary from country to country. You can try contacting your local Samsung via Twitter. But other than them, your only choice is Google.
18mos is the standard support period for most non Google manufacturers.