LPG Portable heaters

Both work well and after the first hour there is little difference in performance. The brick heaters radiate heat to the solid surfaces directly in front of the heater. The blue flame heaters use convection to heat the air, which depending on location, volume and airflow may distribute the heat over a larger area faster. The biggest difference is when you first turn on the heater, the brick heater warms those right in front of it quickly, where the blue flame heats the surrounding air. A side effect is that the front surface of the brick heater gets much hotter, which can be a safety factor for those with pets.
Other than your personal preference for where you want the initial heat concentrated, there is little difference in overall performance, assuming the same BTU ratings.