I auditioned the KRK Rokit G3 studio monitors, including the 5, 6, and 8 models, and compared them side by side with the Yamaha HS5, HS7, and HS8 studio monitors at a local Guitar Center store - I skipped the JBL LSR series because some of them were absent at the store.
I found that the KRK's are pleasing but a bit more warm in sounding, with more emphasis on bass when compared to the comparable models of Yamaha. The Yamaha's sound a bit more neutral to me.
HS5: A bit too much emphasis on highs and mids, a bit weak in bass, would be perfect with the HS8S subwoofer.
HS7: Great stereo separation, great highs and mids, a bit lacking in bass, would be perfect with the HS8S subwoofer.
HS8: A little less clear in highs and mids than the HS7, better bass performance.
In the end, I chose a pair of Yamaha HS8, since I do not plan to buy the HS8S subwoofer.
Thanks,
Paul