RightAngle

Not a Fuji user, but I'll chime in.
 
"Where I live there aren't any places which rent out fujinon lenses."
You are deciding between focal lengths, just rent a camera and a lens from any brand.
 
"If I'm gonna invest in a new lens I have to be 100% sure I won't regret it."
Given that you are not familiar with the relative FOVs, that's not going to happen. If you are that worried, the best solution would be the 10-24 zoom.

What follows is subjective, although most people I know are in agreement.
16mm is actually not that wide, especially when it comes to tighter interiors. The speed will be mostly irrelevant for the purposes you mention, unless you take night shots - stars, auroras etc. It is roughly as big, as heavy and as expensive as the 10-24 zoom. So, you better be sure that you need that speed. It is also weather sealed, but depending on how and what you shoot, that might be completely irrelevant.
14mm is great. It is in the beginning of the ultrawide territory, without being an extreme. It is a nice compact lens, easy to carry around. It also has the smallest filter thread of all of the lenses you mentioned, which will result in cheaper filters in case you decide to use those.
12mm is getting really wide. It is great for tight interiors and landscape, but that wide becomes a bit strange for city shots. One can achieve very interesting results, but it will be of limited use. 
The 10-24 zoom is also very nice, although I doubt the usefulness of the OIS. It is nice to have, but at these focal lengths it won't give you as much. The manual focus is fly by wire, which I find to be a big problem for landscape. It also has the largest filter thread.

Personally, I would take the 14mm. 

To my mind it is very much a case of "Horses for Courses" and there will always be those that favour one brand / format over another.
 
Surely, the aim is to get out, shoot photos that make the taker and those who view them smile and enjoy the image, it is not down to the equipment but the person using it.
 
Even though I use Nikon Full frame for my aerial work, I have now used the Fuji for some sport events and found it smaller, lighter (kinder on the shoulder) and very capable and the combination of new sensor, very capable AFC tracking on the X-Pro2, bigger buffer and other benefits are leading me to consider trading my full frame kit in for the new XT2 if it meets / exceeds the capability of the X-Pro2!
 
I also find that Fuji is very much a "listening" company that takes on board feedback/suggestions from many users and produces cameras photographers want rather than having designers/engineers produce what they perceive we need.
 
All in all I am happy with what I currently use and my future path will be dictated by what Fuji offers in the XT2 based on all that feedback...............either way, the choice of equipment has never been greater than it is now and there will never ever be a one size fits all photographic tool.

Not a Fuji user, but I'll chime in.
 
"Where I live there aren't any places which rent out fujinon lenses."
You are deciding between focal lengths, just rent a camera and a lens from any brand.
 
"If I'm gonna invest in a new lens I have to be 100% sure I won't regret it."
Given that you are not familiar with the relative FOVs, that's not going to happen. If you are that worried, the best solution would be the 10-24 zoom.

What follows is subjective, although most people I know are in agreement.
16mm is actually not that wide, especially when it comes to tighter interiors. The speed will be mostly irrelevant for the purposes you mention, unless you take night shots - stars, auroras etc. It is roughly as big, as heavy and as expensive as the 10-24 zoom. So, you better be sure that you need that speed. It is also weather sealed, but depending on how and what you shoot, that might be completely irrelevant.
14mm is great. It is in the beginning of the ultrawide territory, without being an extreme. It is a nice compact lens, easy to carry around. It also has the smallest filter thread of all of the lenses you mentioned, which will result in cheaper filters in case you decide to use those.
12mm is getting really wide. It is great for tight interiors and landscape, but that wide becomes a bit strange for city shots. One can achieve very interesting results, but it will be of limited use. 
The 10-24 zoom is also very nice, although I doubt the usefulness of the OIS. It is nice to have, but at these focal lengths it won't give you as much. The manual focus is fly by wire, which I find to be a big problem for landscape. It also has the largest filter thread.

Personally, I would take the 14mm. 

Not a Fuji user, but I'll chime in.
 
"Where I live there aren't any places which rent out fujinon lenses."
You are deciding between focal lengths, just rent a camera and a lens from any brand.
 
"If I'm gonna invest in a new lens I have to be 100% sure I won't regret it."
Given that you are not familiar with the relative FOVs, that's not going to happen. If you are that worried, the best solution would be the 10-24 zoom.

What follows is subjective, although most people I know are in agreement.
16mm is actually not that wide, especially when it comes to tighter interiors. The speed will be mostly irrelevant for the purposes you mention, unless you take night shots - stars, auroras etc. It is roughly as big, as heavy and as expensive as the 10-24 zoom. So, you better be sure that you need that speed. It is also weather sealed, but depending on how and what you shoot, that might be completely irrelevant.
14mm is great. It is in the beginning of the ultrawide territory, without being an extreme. It is a nice compact lens, easy to carry around. It also has the smallest filter thread of all of the lenses you mentioned, which will result in cheaper filters in case you decide to use those.
12mm is getting really wide. It is great for tight interiors and landscape, but that wide becomes a bit strange for city shots. One can achieve very interesting results, but it will be of limited use. 
The 10-24 zoom is also very nice, although I doubt the usefulness of the OIS. It is nice to have, but at these focal lengths it won't give you as much. The manual focus is fly by wire, which I find to be a big problem for landscape. It also has the largest filter thread.

Personally, I would take the 14mm.