The reasons that will make me change my AV.
1- Compatibility issues with other software.
2- False alerts- I hate false positives when an AV starts detecting my safe programs then it is time for it to go.
3- Makes system have slow response time or slow web browsing.
4.-Unresolved annoying bugs.
5.-Requires constant tweaking, configuration changes or manual upgrading.
For protection or detection: All will fail to block infections if you are reckless and download suspicious files and you can get infected using any AV, therefore this is not a consideration for me to change my AV.
AV tests and reviews don't really mean anything since it is impossible to test every single malware on the web.
Testing small samples will not determine how well any AV will protect you.
Enjoy!!