What to make: a film, short film, series, web series? I'm an independent indie film-maker with a strong ambition to advance onward, and I have no contracts whatsoever. 

Is it better for me to create a feature film, short film, series, or a web series? 

(This isn't exactly a question about opinions or one's thoughts.)

Which is more likely to be more successful, beneficiary, have a fan-base, and has a bigger revenue model, or which one is more valuable?

The thing I have in mind is a long story. Thus, I would perhaps want to eliminate the option of short film from my list.

How difficult is convincing a channel to broadcast a series with directors they do not know or have never heard of, or from another non-English speaking country.

Thanks.
One advantage to a web series is the absence of a gatekeeper. That is, you can upload (pretty much) anything you want to YouTube. You don't need to convince the website owner to include your work; you don't need to convince a TV station or movie studio to invest. In addition, sites like YouTube and Vimeo have built-in audiences.

To get a significant number of views, you would still need to do a lot of online promotion of your work by contacting bloggers, contacting "aggregation" sites that feature work like yours, posting on Twitter / Facebook / Reddit, and so forth.