There are quite a few factors depending on how much current, voltage boosting to, switching frequency, and at what point in the loading profile for a given power capability.
Usually, switching device is #1, followed by coil losses. A passive rectifier has between 0.4v and 1.1 vdc drop so whatever your output voltage is, the boost is effectively producing a diode drop above this output. You can do an active syncronous rectifier to reduce this loss. For lower voltage the syncronous rectifier makes more sense since a passive rectifier voltage drop is a higher percentage of output voltage.
Switching frequency decision is complicated mix of factors. The faster you switch a MOSFET, the more driver power is consumed so low end efficiency will suffer. There are methods to mediate this.
A good online presentation is at:
**broken link removed**