Is there really such a thing as "best for rock", "best for jazz", etc.? Isn't it more likely that a better speaker is simply a better speaker, regardless of what style is played on it?
Yes and no. A perfect speaker would be perfect for all types of music. But in the real world, people can only pick what is possible, and that means that they generally must keep the price down. So they are left with making compromises in the sound quality. Which is more important, deep bass, or a more "refined" sound? Or is maximum volume most important?
I own Aurum Cantus Leisure 2SE U.S. version speakers (beware of sellers on eBay, as I have seen people claim they are selling this version when in fact they were selling a lessor version of this speaker, which has been available in
at least 4 versions under the Aurum Cantus name, and a couple of other versions under other brand names). You can read about the newer U.S. "Signature" version at:
http://www.kellsieavdesign.com/products/Leisure2SE.htm
The "Signature" version is the new U.S. version; the ones I have are no longer made, but most closely resemble these of the versions one can now obtain new. The "Signature" version is supposed to be better than the older U.S. version that I have, and probably are slightly better, though I have never heard them and cannot be certain.
Now, I really like them. And I like them for all kinds of music, including rock. But, someone who wanted rock concert, hearing damaging levels of sound in a large room would not be happy with them. Nor do they go as low as some other speakers that one can get at their price. And, having ribbon tweeters, the sound is more directional than many speakers (I have some old JBL Model L36 speakers that have incredible dispersion, though still not omnidirectional, as some speakers have been). But, in my opinion, they sound very good indeed, and are the best speakers I have heard at their price point (please note, others value different qualities in speakers, and consequently their preferences will differ from mine).
When I was younger, and listened basically just to rock music, and was on a much tighter budget, I bought some cheap speakers that had 15" woofers. The bass was abundant, but "sloppy". At the time, however, they were a good choice for me, given what I was listening to AND my very tight budget AND what mattered to me at the time.
So, the "best speaker" for rock, at a given price point, might not be the same as the "best speaker" for listening to classical solo piano music. Of course, it also depends upon what one values in the speaker, such as ability to play loud, or ability to deliver very deep bass, or having a wide dispersion, or having minimal distortion, or whatever. So there isn't going to even be one "best" speaker for one type of music at a given price point, as different people value different characteristics. Generally speaking, though, the ability to play bass loud is important to people who ask for a "rock" speaker, and usually they are willing to sacrifice some detail and refinement for it.