Haiku has the most cozy UI skin I can name (I have also seen some even prettier but that was something completely exotic and I don't even know what OS that was)

Haiku has the most cozy UI skin I can name (I have also seen some even prettier but that was something completely exotic and I don't even know what OS that was), another one of this kind was QNX 6.0 Photon desktop. An the same time when it comes to icons - I enjoyed Windows 3.11 the most (Windows 98 was not bad too).