different types of smps
the actively cooled would be more efficient

I disagree, since the actively cooled SMPS needs that extra cooling and the airflow from the fan it could be (and probably is) less efficient than the fully closed SMPS.

The fully closed SMPS does not have this extra cooling. Assuming both SMPSs are well designed the closed SMPS needs to be more efficient as it cannot dissipate as much heat as the SMPS with the fan.

The increased effciency can be achieved by using a better design and/or better components which will very likely make the closed SMPS a little more expensive. However, a fan also costs money so in the end their prices could be quite similar.

As commented, a fan can fail and dust is an issue. Such a cooled supply does need some maintenance every now and then. I make it a habit of blowing out the dust at least once a year for my server which has an actively cooled SMPS.

The closed SMPS will still get warm so you have to give it some "breathing space". In my experience the closed SMPSs from reputable brands are very reliable and do not run very hot. My choice would be the closed SMPS!