In terms of traffic most people react the worst to aeroplanes. It may be fun spotting some aeroplans at a spotting spot such as the one in Kněževes, but listening to this will stop being fun very soon.
The worst noise happens if you have a plane taking off or lending directly above you, which may happen for instance if you choose a land near Unhošť or other locations that are in the direction of the runway. Prague Airport plans another runway.
If you hear the term “ochranné hlukové pásmo letiště” meaning airport noise protection zone, this actually refers to the area of permanent noise where the airport noise is protected, not the people! In case of Prague Airport, this zone is described and depicted at a website of a Prague district Suchdol.
There are a few other airports in Czech Republic, most of which are meant for very small sport aeroplanes, and those tend to be harmless.
One other airport to take note of is Letiste Vodochody because of the initiative trying to make this a large commercial airport for low-cost airlines (see e.g. the official website). The local municipalities are trying to prevent this, and even though currently they are succeeding, there’s always a risk of the airport realizing and then the general area will be very much affected.
There’s many areas which are far from any airport but still suffer from aeroplans flying over. as these areas are in the typical “air corridors”. Even though the noise will not be comparable to the noise from low-flying aeroplans near an airport, it’s still a nuisance to consider.