Street about 50cm above the property - backfill or basement

Hello dear house-building community,
I have been reading diligently here for a few months now and now it’s starting for us too

This week we bought a plot of land from the municipality in a new development area (Northern BW).
We chose this desired piece because, unlike the others, it is "flat." (The rest of the area is mostly on a slope (south or north), we chose the saddle)
Info about the plot see below
Because of the modest ceiling height of 4.1m, we will have a knee wall of about 1-1.2m and the choice fell on a flat plot, we decided to build without a basement, as we would like to make the house so large that it simply works upstairs (160-170sqm base area = 140-150sqm living space depending on knee wall) plus a garage or carport with boundary development.
That was the plan... I noticed something while measuring the plot myself with a ruler on the digital subdivision plan: The planned street is at the sight break at 303.49, i.e. at least 50cm above the plot level.
We asked our three builders about this (one of whom will hopefully be chosen in about 4 weeks)

Response from prefabricated timber frame house: The slab works wonderfully, the house will sit higher anyway due to the gravel foundation
Response from prefabricated solid house: Please build with a basement, then you can use the excavation material for filling. Otherwise, you fill the plot for 15,000 euros without any return. Besides, being below street level is always bad because of rain.
Response from architect of a general contractor (solid, stone on stone), who is the top dog around here: Forget the basement because of possible rock and landfill fees, I can even get your knee wall up to 1.50 and you don’t really have to fill up. I also see no problem if you are slightly below street level.

Three answers, but I’m not any wiser now. (The only thing was that my wife did little jumps of joy when she heard 1.5-meter knee wall)

We would place the house as far north as possible and then the garage/carport towards the east to the neighbor
I have attached a section of the plot (including target and plan contour lines).
I am currently hoping here for or , as we are at a loss.

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Development plan/restrictions
Size of the plot: 451sqm
Slope: 60cm over 20m (rather even less)
Site coverage ratio: 0.35
Floor area ratio: none defined in the development plan
Building window, building line and boundary: Building window see attachment, otherwise 3m to neighbor
Boundary development: no
Number of parking spaces: min 2 required
Number of floors: 2
Roof shape: SD, vSD (30-40 degrees)
Style: classic
Orientation: either parallel to the boundary or ridge direction see development plan
Maximum heights/limits
Ceiling height: 4.1
Full height: 8.9
Other specifications:
Miscellaneous (tree planting types etc.) but nothing relevant to the house
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Architect is right. If you don't want a basement, leave it out. Saves 80k. With this plot, no problem, 50cm is nothing.

Number of stories: 2
Roof shape: SD, vSD (30-40 degrees)

TH: 4.1

A predetermined two-story design with these specifications: There isn't much room for maneuver, especially considering the plot size. I'm curious how the house must (not can) look.

You can definitely do without a basement here when it comes to the level.

Where the construction starts depends on the existing ground. So maybe remove 15 cm of topsoil and store it to the side. Then 30-50 cm of gravel, insulation about 10 cm, 25-30 cm slab. That already puts you 40-80 cm higher. However, only in the area of the house. Adding topsoil arbitrarily does not make sense, but spreading some around the rest of the site would probably be fine.
It can also be different if you have to excavate a meter or more to reach load-bearing soil. So have a soil report made.

My gut feeling tells me I would not like to be below street level. I like water, but preferably in connection with a lot of sun and palm trees, alternatively in the pool, but not otherwise in or around the house when it rains.

The other houses are located on the slope, yours in the hollow; when it rains like on the Mediterranean, who has the water from several properties and from the street? The weather extremes and frequencies are increasing

you in the depression,

No, not depression, but the saddle, that is the highest point.