According to him, those Tidal, Kharma, YG, Magico, Vivid G1, Grande Focal and German Physik are truely good speakers, JBL ain't no good...and his reasons: JBL is boxy, horny coloration as hell, zero imaging.
is this true?
It all depends on what one is looking for in an audio system.
If one is looking for that big, dynamic, lively "rocking" sound, the JBLs might be a good choice.
But, if someone is looking for a more detailed, open, more neutral, more accurate (timbre, harmonically), better imaging, speaker, the others will do that better. At a substantially higher price.
As you might have surmised, I agree with your friend.
JBL speakers come of as a bit of a 'blunt tool' to me. They make everything sound as it it is coming from a high quality PA system. They don't get out of the way of the music, they always impart their sound.
Also, I agree, that they offer no real imaging. They create a big wide soundstage, but no real layering, or imaging, within that soundstage.
I have heard: Everest's, Summit's, L100's, and a few more.