Which bathtub shape should we choose?

Addendum: I don't know how tall you are and whether you use the bathtub alone or with someone else: even more important to us than a round 'snug' shape was the height of the bathtub. This is 52cm, most others are at 45-46cm. Even with two people at a height of 1.75m and 1.90m, the knees are always nicely in the water. We love the tub and bathing

We also really enjoy bathing together. The height is of course also an argument. The cushions are great, I can only recommend them to you. There are expensive ones directly from the brands, but we have cheap ones with suction cups, that's enough.
That the round shape is better for the shoulders is definitely an argument.
Having the choice is a dilemma...

Without trying, nothing works at all. While Curly finds the round shape uncomfortable because it feels constricting, the inside cornered one didn’t work for us at all. It always depends on the shape of your back and how you want to lie or sit. For example, we have one side round, one side for standing (for quick showers), but the two of us can bathe together comfortably. Nobody looks at the appearance (in stylish or more stylish) later on, that has to be mentioned sometimes. Edit: we also paid attention to the height: 3 cm already makes a big difference. We have a Bette in [Stahlemail] 180/80 and bathe a lot.

Just read for the first time in my life about a pipe breaker, which is apparently needed for the bathtub if you have a rotary knob with overflow on top. Does anyone of you know if you have installed it? According to the description, it is visible

Absolutely try it out first. There is no other way. We found it important that the tub is rounded/stepped at the top. That makes it extremely comfortable.

For example, [Hoesch Spectra] is very comfortable and stylish.

I just read about a pipe breaker for the first time in my life,

What is that supposed to be? In our case, the plumber did the installation, we didn't order any extra thing.