You'll probably have time to try both. First go to the non-Schengen lounge, it's definitely better and most probably also less crowded than the Schengen lounge. As you have to allocate enough time for passport control, you'll probably end up with some time to spare also in the Schengen lounge, if the passport control is quick enough. By spending at least an hour in the non-Schengen lounge, the arrival wave should be already over by the time you need to go to passport control, unless some of the arriving flights are delayed.