«experimental rock» - best artists
Experimental rock or avant-garde rock is a way of referring to music that can mean pretty much anything original done within the context of a particular genre. Using unconventional time signatures is common in progressive rock, jazz etc so not really experimental in itself. Using feedback has been common (on and off) since the days of the Velvet Underground and Hendrix, moreso since Noise Rock evolved after Punk. Music with longform non-pop or no song structure whatsoever has existed at least since the days of 60s/70s psychedelia and space rock, and was a fairly routine way of perfoming in styles such as jazz years before that. Combining electronic elements or samples with rock music likewise has a long tradition dating back at least as far as to the earliest Industrial musicians, to the extent that if you call a lot of post-rock bands experimental you ought to call Limp Bizkit experimental too. Bands who perform highly uncommercial, unpredictable and “difficult” music are most likely to be avant-prog artists or from Japan. It is considered more closer to alternative rock than progressive rock.