Confused about Niches

How do I know which niche to pick?
To me it seems like everyone of them is already taken and saturated with content. Is the strategy just to`spam' my link out more than others so my site is found first instead of theirs?

Even if I do find a keyword that has very low google search results it seems like someone has already setup a website for that and is on page 1, also if nobody is searching for that keyword, what is the point of even ranking for it?

I know how to get a domain, hosting, content, backlinks and I have also built up a few social networking accounts, but I just don't know how to decide what niche to pick and get started on.

I'm not asking for a niche or keyword but I just want to know what criteria you use or how you decide on which one to chose.

The best answer is what niche you are perfect. Writing content by your own makes it one day a great blogger. Any niche anything is hard unless we put great content on the internet.
My suggestion is to build a blog or site that you are interested.