According to the search query at HP on your printer Office Jet Pro 8710

https://store.hp.com/Switzerlan...

953 and not 963 cartridges are listed as accessories.

You can find these cartridges at digitec under

https://www.digitec.ch/de...

The cartridges with XL as a suffix have a larger filling capacity and are, on balance, cheaper per printed page. However, this is only the case if you print regularly.
If you print infrequently, there is a risk that the ink will tend to dry out or stick together, resulting in poor print output.

Recommendation:
- Buy cartridges without XL if you print infrequently or if the printout is poor due to ink drying/sticking.

- Buy cartridges with XL if you print regularly, then daily or almost daily use will prevent drying out.