Passive cooling is generally better for reliability if you can make it work, since all active airflow systems will degrade as dust and hair works into the airflow paths.
Plus, the two can be used in combination. Improved passive cooling systems will make active cooling better by reducing the need to run the active system all the time, or at least run it at reduced rates, which will make the whole system last longer and reduce maintenance.
Passive cooling is generally better for reliability if you can make it work, since all active airflow systems will degrade as dust and hair works into the airflow paths.
Plus, the two can be used in combination. Improved passive cooling systems will make active cooling better by reducing the need to run the active system all the time, or at least run it at reduced rates, which will make the whole system last longer and reduce maintenance.