I download symbols and footprints from the component supplier into a project's library to go faster but I realized that many of the standard components footprints are slightly different in KiCad, like for example the SOT-23-6 so my question is: is it better to stick to KiCad footprints or just use the suppliers footprints?
There is more to good footprints than just "matching the pads to the pin". Depending on the dimensions and distances the results of soldering can strongly vary. Good footprints can reduce the risk of shorts and grave stones for example.
From my personal experience, I strongly advise using the IPC-7351 footprint recommendation because the standard library coming with KiCAD did not really live up to the expectations (at least back then I started) and even the footprints described in datasheets sometimes resulted in less optimal (reflow) soldering for me.
There was a rather prominent repository of a KiCAD library derived from the IPC-7351 recommendations but I cannot find it anymore. However, it seems like there is still a version around https://github.com/alexisvl/kicad-pcblib . I typically use the "Least" but only because I do a lot of tiny crowded PCB with reflow soldering. The "Most" version should be adequate for everyone with decent knowledge about hand soldering.