Hi all and thank you for all the information and good answers! 

I have been looking at the antminer s9, it's relatively expensive but seems to have much "power"

So I am thinking of buying one S9 or maybe four S7, when considering the hash power it looks like four S7 will mine more efficiently then one S9.  Any thoughts here?   

The electricity is not a problem because this will be a cost I don't have to worry about. I want to setup this rig as a "test" and to learn more, but I also of course want it to be profitable tho show results.

So to tell you why I am looking in to this: I have an idea together with my fellow colleague and co-founder of our marketing company to build an mining farm. We have a unique "facility" nearby with hydropower.

This is a cave and it was supposed to be a server park for Apple and the cave was transformed to fit their specifications, but they lost to another facility.

We want to build a huge mining park here with investors and other people with more experience than us in cryptography and currency.

But I would like to build a small mining rig to show results and to learn from it myself, so learning by doing! The budget for the test rig can of course be increased if that is necessary.

I am sorry for not responding earlier but it was something bugged with my thread and I couldn't see the answers until now.

I was hoping someone here could give me some quick tips on mining as I am a beginner.

I am a crypto invester but still a beginner when it comes to cryptocurrency!

I would like to start mining to get experience and I was wondering what coin is the easiest and at the same time most profitable to mine?

I have done some minor research and found that the most profitable coin to mine is as the list below.

1. Bitcoin
2. Etherum Classic
3. LiteCoin
4. Dash
5. Monero
6. Etherum

Which of those is easiest to mine? And do you have other suggestions? What type of mining rig should I setup?

I want something small to begin with (corner of an office) so that it doesn't take up to much space, and I don't want to use much more than $4000 to begin with.

Appreciate all help!