Right query to get the current number of connections in a PostgreSQL DB

Question

Which of the following two is more accurate?

select numbackends from pg_stat_database;

select count(*) from pg_stat_activity;

Answer 1

The following query is very helpful

select  * from
(select count(*) used from pg_stat_activity) q1,
(select setting::int res_for_super from pg_settings where name=$$superuser_reserved_connections$$) q2,
(select setting::int max_conn from pg_settings where name=$$max_connections$$) q3;