If you are unsure which system you should install, the clear recommendation is currently to install grapheneOS on one of the compatible phones. However, this is not possible for everyone, as these devices are relatively expensive. In addition, some people do not want to support Google financially with their purchase. In addition, non-replaceable batteries and the difficulty of repairing the devices can be reasons to decide against Graphene.
There are therefore a number of other alternative operating systems such as CalyxOS, /e/OS or LineageOS, which are more independent but do not necessarily focus on security and data protection. Nevertheless, this can also be a way in the right direction towards more independence. The individual alternatives are listed below: