unmanaged VPS :
i have been using Digitalocean for some of my blogs built with wordpress, i have experienced with many open source cpanel alternatives like Zpanel,kvm,webmin,virtualmin etc.. & used for my
unmanaged VPS.

Even i used ubuntu,centos etc.. i am still confused ,which os i have to use ? weather it is ubuntu or centos or debian.After some research i found that, its not about OS, its all about server ? weather i have to install apache or nginx.& also its all about optimization of our website, Good code,mysql configuration,& also keen observation on our un managed Vps.
Which server for my unmanaged VPS ?
Nginx on unmanged vps :
i have installed nginx server, & ran a wordpress blog, after 1 week time, my mysql stopped, i got a doubt, just i am using 1 wp blog, why the mysql stopped, the blog is getting maximum 25-100 page views per day.
i restarted my server ,the mysql started again. i have observed when more cpu is consumed , my mysql will get stop & i will get a wordpress error, UNABLE to connect Mysql Database.”
Apache for WordPress using blue host & comparison with digital ocean ( unmanged vps):
So i planned to use Apache server, after some days the same problem happened again,Now what i have to choose ? So i purchased a hosting at bluehost & hosted my blog there.You can also choose Hostgator hosting. My blog time response was now 6.6 seconds. Where as, at digitalocean the blog loading time is only 3 seconds shown in alexa within 2 days.
unmanged vps or Manged Vps ?
if we buy managed vps , we can get that speed, it will be costly to buy a managed vps with 1gb or 2 gb ram. if we buy un managed vps ,we have to manage our own server & you have to hire a technical person like me to solve the issues. So i am still learning more to mange & maintain unmanaged vps. Choose Ubuntu or Cent OS for you hosting, install Apache or nginx & mange the server.
if you have good experience with unmanaged vps please share your views via comments.