If you are familiar with hosting control panels, shell commands, and you have basic server administration and troubleshooting skills, then unmanaged VPS is the way to go. Note that while you purchase self managed VPS, you should be capable of managing applications, software, services installed on your VPS. Also, you must know installation/uninstallations, resource monitoring, server performance tweaking and troubleshooting of any technical issues.
However, if a bad user shares your server with you, they can threaten your security and allow hackers to easily reach your content and critical data. Furthermore, because you’re all sharing the same resources, if any of the users that you’re sharing your server with use a lot of memory or their site has a lot of traffic, your website’s performance is likely to suffer.
Think of a shared server as a large apartment complex, and all of the individual apartments are rented by other website owners. All of you need a place to live — just like your website’s files — but going out to buy a huge family home would be too expensive for your needs. Sharing common areas and utilities in an apartment block helps keep costs down. And the same is true for shared hosting.