Google Now Does Not Work for Some Users on Nexus 5

Android 4.4
Google Now Widget

In many places I see complaints about Google Now not working on Nexus 5. However, I think relatively only a few users have this problem, or people did not even notice it yet.  I read some suggestions, and a lot of nonsense related to this issue. I also talked with enterprise support, this also did not pointed me in the right direction.
After several days of changing settings, I came to the conclusion that I would not get Google Now working this way on my Nexus 5.
My Nexus 7 got the OTA to Android 4.4, afterwards I did a factory reset. Signed in and Google Now was not working. Played around in account settings, Google Apps settings. Nope nothing worked.
With the knowledge of my Nexus 4 & my Nexus 7 both on Android 4.3 had no issues with Google Now. I concluded it must have something to do with KitKat Android 4.4. Well not really.
Signing in with different Google accounts, wow Google Now is working! Unfortunately not with my main account.
So now you think, it's account related. Well not entirely... Knowing that, not having Google Now problems with Android 4.3 on my Nexus 7. I flashed the Nexus 7 with the factory image Android 4.3. Now I could setup Google Now with my main account, did the OTA update to Android 4.4, and yeah, Google Now still working! Even with the Google Experience Launcher!
One down, one to go. I can not do the previous steps on my Nexus 5, because there is no Android 4.3 image. Since Google Now is included in the Google Search app. I had to try downgrading the Search app to version 2.6. Unlock (fastboot) -> Root (Chainfire) -> Uninstall Search 3.x (Titanium Backup) -> Install Search 2.6 -> Setup phone with Google Now -> Lock (fastboot). Yeah Finally, Everything working as it should! Not the way I like it, but still.

Final Conclusion

This issue is combination issue between some Google Accounts & Google Search 3.x.