I saw Apache server is not suitable for raspberry Pi because of security
Could you link us to wherever said that? Sounds like nonsense to me. Apache on the Pi is the same as Apache anywhere else. It's plenty secure enough. Of course, like anything else, one can configure it badly and blow that security.
I wanted to use that server, which most people use to make project
I think you should review your selection criteria a little bit.
It is helpful to use popular solutions that many other are using. That ensures you will probably find it much easier to find documentation, tutorials, blogs, forums etc for support.
But I think the first criteria is what actually is it you want to do?
If you want a general purpose web server, say with PHP and a database behind it then perhaps the traditional Apache stack is the way to go (LAMP).
If you want a server for a single application then perhaps you can skip Apache or Nginx and just create that server in your application. Here node.js is my choice. Python heads will use Flask or whatever. Java guys will bog themselves down with the complexity of Tomcat.
I'm sure all of these are widely used and support is plentiful so I would not worry about that so much.
Me, I use multiple web servers. At the front end there is nginx which serves up what it can and proxies other requests to other servers. Apache if there is an application in PHP or whatever built for Apache, node.js for more specific application servers.
For speed I would stay away from Python, for simplicity I would stay away from Java, as far as is possible. Hey, but that is just me.