Are you going to be hosting an app, website, ..., etc.? Will MySQL suffice? Or will your apps, website(s), etc. require features that are not found on MySQL, but on other opensource databases? Why are you choosing Apache over Nginx? and so on; and so on.

What's the objective?

You're essentially asking "What is your thought on the below [hammers]? and what do you advice? any better performance?

1) sledge hammer? and why?
2) ball-peen hammer? and why?

The point here is that the more details your give about your particular situation, the better quality responses you'll get (at least, hopefully).

Please DO NOT duplicate your questions.

https://www.digitalocean.com/community/questions/xcache-vs-apc-at-a-apache2-mysql-php-already-using-memcache

Hello pablo, some light to your questions

Are you going to be hosting an app, website, ..., etc.?
---> I am going to host a heavy traffic set of classifieds sites

Will MySQL suffice? Or will your apps, website(s), etc. require features that are not found on MySQL, but on other opensource databases?

----> I will mainly be using MYSQL and all the data are write/read from/to Mysql and it is why Memcache is super important here

Why are you choosing Apache over Nginx? and so on; and so on.

-----> For now, choosing Apache over nginx because My actual Dedicated server was set up under Apache and the sites heavily depend on apache rewrite and moreover I do not yet have nginx knowledge

What's the objective?

-----> the objective is to have good website with less load time possible

Regrads
Jacques