Water softener - What should be considered? Recommendations?

Hello everyone,
we have just finished the tenders for heating, ventilation, and plumbing and have received offers for various water softening systems. Besides BWT AQA Perla (2-column), also a Grünbeck SoftliQ-SC18 (1-column). What have you decided on and why? Can you recommend anything? So far, my requirement was "softer water" than 19 degrees dH to deal less with limescale in the bathroom and washing machines and to make a decent espresso from the dual boiler. Ok, the latter would also work with mineral water, but that’s not the topic [emoji6]
I understand that system-related, the sodium content of the water increases because calcium ions are exchanged for sodium ions. But that’s about all my knowledge. In your opinion, what else should be considered?
Thank you very much and best regards,
Stephan

There are two systems: 1. The ion exchangers that exchange calcium for sodium ... sodium content increases. 2. The so-called crystallizers. Calcium is bundled into larger pieces that can no longer settle as limescale. Advantage: No chemicals, no ion exchange. Coffee tastes the same as before. Basically, it is a matter of belief, we chose solution 2 because of the lack of chemicals. Friends of ours also have this and you can’t taste any difference, whereas acquaintances with solution 1 had a second water connection "Natur" installed in their kitchen for drinking water.

Grünbeck because the plumber services it.

BWT was only supposed to be sold and installed. Maintenance would only be done through customer service which is insanely expensive.

There are two systems: 1. The ion exchangers that exchange calcium for sodium ... the sodium content increases. 2. The so-called crystallizers. Calcium is bundled into larger pieces that can no longer settle as limescale. Advantage: no chemicals, no ion exchange. Coffee tastes the same as before. Basically, it is a matter of belief; we chose solution 2 because of the absence of chemicals. Friends of ours have that too and you can't taste any difference, whereas acquaintances with solution 1 have had a second water connection "natural" installed in the kitchen for drinking water.

How much do both solutions cost? My wife actually wants to have that.

Both solutions were about the same for us. Only the device Biokat 3000 €2145 without commissioning and installation. Replacement cartridge every 5 years for €285.

We have decided on the Grünbeck SC23. It costs €1799 and €50 for installation by a friendly plumber.