Both the Salon2’s and Genelec’s are good at phantom center image, in different ways. The Salon2’s have wider beam, so sound attenuates more gradually (yet still with consistent tonality) across the horizontal plane, but in most other respects the Genelec coaxials are better: more consistent tonality not only vertically, but tonality that remains extremely consistent at almost any distance from the speaker.
For example, I can sit on the floor at the center point between my Genelec 8361A’s (significantly off-axis both horizontally and vertically, in addition to being very close to each), and they sound great and still relatively uncolored. The same is definitely not true for the Salon2’s or any other traditional non-coaxial speaker. The phantom image of the Salon2’s remains more stable when extremely unnaturally close to them (e.g. if you stand directly between them) due to their wide beam, but in this situation their overall tonality (despite the stable phantom center) becomes much more colored than the Genelecs at the same close distance.
In other words, the Salon2’s are extremely consistent in tonality and attenuation across the horizontal axis, while the Genelec coaxial are more consistent with tonality across all axes (especially vertical and radial/distance) at the “expense” of a narrower beam (attenuates quicker off axis).
As long as your listening position is a few meters out though, there isn’t really any noticible difference in phantom image quality (though the ratio of direct to indirect sound is very noticeably different). If you listen extremely close to the speakers, the Salon2 phantom center image is better but the Genelec’s overall tonality is much better (whereas the Salon2’s direct sound will start sounding unnatural when you’re that close).