Double garage on the east or west side?

It is a north/south edge plot with access in the north, with greenery/a side street in the east and a neighbor in the west. The neighbor has placed a double garage on the boundary. Where would you plan your own 6x9m double garage if there is still 5m of space left on the respective other side? Would you prefer to look at the greenery from the living room window, or at the neighbor's garage? On one side of the house, a ground floor window would have to be omitted because of the garage...

The question is difficult to answer.

I tend to place the garage on the west side - on the one hand, the view is anyway impaired by the neighbor's garage, on the other hand, the west side is the weather side.

However, you should possibly make the decision dependent on other things: What is located in the east (which view)? Which side could you more likely use to relax (west side, since you want to enjoy the afternoon sun; east side, since you have breakfast on the terrace on weekends and start work late or it doesn’t matter because you come home from work when it is already dark :confused.
However, I’m not quite clear about your comment regarding the living room? Is the living room planned on the west side - if yes: would the living room become too dark with the loss of a window?

You can't really say that in general. I would also depend on the floor plan.

We are putting our carport on the west side because I don't like windows on the west side due to the low sun (at least not in living rooms).

The terrace is planned on the south side. Neither on the east nor on the west would we lay a terrace next to the house, but rather an additional parking space for, for example, a caravan or trailer.

For this, one could additionally build a carport in the west between the house's wall and the neighbor's garage. Unfortunately, boundary construction is only allowed once, and a double garage would definitely be a dream!

The possible garage in the west would be built staggered to the neighbor and not start at 3m like theirs, but at about 5m in order to still be able to park in front of it. It probably also looks better visually.

If we then go to 9m in length, we would also have an overhang to the house of about 2m.
This could, of course, act as wind and privacy protection, but it also somewhat blocks the sun.
In the east, this problem would not exist, and the property would be closed on both sides.
But then we would also not want windows facing west, because after 5m the neighbor’s garage wall already comes.
It is really not easy....

No windows at all on the ground floor facing west? Can you show us floor plans and your house positioning on the property? Then maybe one can say something about it.

The terrace is planned on the south side. Neither on the east nor on the west would we create a terrace next to the house, but rather an additional parking space for e.g. a caravan or trailer.

For this, a carport could be built in the west between the house wall and the neighbor’s garage.
Unfortunately, a boundary development is only allowed once and a double garage would really be a dream!
The possible garage in the west we would build offset from the neighbor and not start at 3m like theirs, but rather at about 5m, to still be able to park in front of it. It certainly also looks better visually.

If we then extend to 9m in length, we would also have an overhang to the house of about 2m.
This could of course act as wind and privacy protection, but would also block some of the sun.
In the east there would be no such problem and the property would then be closed on both sides.
But then we would also not want windows facing west, because after 5m there is already the neighbor’s garage wall.
It’s really not easy....

Since 1. I lack spatial imagination and 2. I have little time, here is a brief note from me:

Some municipalities have the construction requirement that a “captured” parking space is not permitted or that an additional parking space must be available.
A captured parking space arises, for example, when two cars park one behind the other, but one car cannot leave without the removal of the other vehicle. That’s why we, for example, had to provide another parking space.