I kinda liked the the way we had the qualifying done in LXCC, only bad thing being the small time of actual track time versus the time it takes to run the quali. But I defenately liked the pressure of the system.
Other than that, timed quali is good too, more track time and probably better times as well. Less surprises with the grid though :/. And a small strategy element introduced when you need to find a good spot to do a good lap between the other drivers.
Basically the single lap quali is the most entertaining one but imho a 30minute quali session with unlimited laps is most fun in the end. Most track time being the decisive factor