@serra The special “C” collation, as it’s the simplest one that just calls memcmp. If you need something more complex then a default won’t do well anyway. There are many parameters you can choose from, besides case-sensitivity, such as language and whether to recognize multi-digit numbers.
I had a somewhat interesting bug at work regarding case insensitivity: https://dev.direkt-gruppe.de/2020/09/28/ccccc/