What is the most common role that has access to almost all platform features, functions, and data?

The `security_admin` role is a specialized role for elevated security operations, not a general administrative role with pervasive access to almost all platform features.

`Sys Admin [sys_admin]` is not a standard out-of-the-box role with the broad access implied by the question.

The `Admin [sn_admin]` role is the most powerful and comprehensive administrative role in ServiceNow, granting access to nearly all platform features, configurations, and data, which allows for complete management and control of the instance.

While 'System Administrator' is the common display name for the highest administrative user, and `admin` is the core role ID, the choice `Admin [sn_admin]` specifically identifies the comprehensive administrative role in the context of this question.

`Base Admin [base_admin]` is not a standard out-of-the-box role with the comprehensive administrative access described.