The front-most longwise curvature ("spin rocker" - NOT the same as the main rocker that applies to the rest of the length) on Jackson Ultima Dance blades (like most Jackson Ultima blades vs most MK and Wilson blades) means you have much less angle and distance to roll between the sweet spot and touching the toe pick than on MK Dance. It took me over a year to get used to that, and I initially hated it.
In addition, MK dance blades are "thin-line", meaning they are ground substantially thinner at the bottom working area - which seemed to me to mean they were faster. The Ultima Dance (I have the now very old and no longer manufactured Jackson Ultima Dance Matrix I interchangeable blade system - I bought enough of them to last a lifetime) were not ground as thin.
I loved MK Dance, but, when I bought most recently, Jacksons were much cheaper - not sure if that is still true.
I've never used Paramount.
Almost all the skate techs I have spoken to agree that Jackson Ultima blades, and possibly Paramount blades, are ground to a much more consistent shape, and have a much better quality edge, than MK and Wilson blades. To some extent, it is helpful to have a very expert skate tech to correct any issues that exist in MK and Wilson blades - though you should also note that they reshape the blade to what they think the shape should be, so the shape you get on an MK or Wilson blades has as much to do with your individual skate tech as with what the factory does - which means that individual results may vary, a lot. OTOH, many of the better blade techs are sufficiently satisfied with consistency of sharpening of the factory grinds on Ultima and I think Paramount blades that they don't alter the factory shape much if at all.
Incidentally, the very sharp edge on the factory grind of Ultima blades extends to the toe pick and the part of the blade very close to the toe pick. Since most skate techs never sharpen these areas, that affects the way the toe pick and to some extent the area next to the toe pick works, for the lifetime of the blade. (A lot of people think the area right next to the toe pick never touches the ice, because it doesn't touch if you put it on a rigid surface, so they call it something like the non-skating area. But if you use a pencil to mark the bottom of the blade, the pencil mark does in fact wear off there - apparently, when you skate, the blade cuts in enough that it touches. That's more true on blades that you jump on, like freestyle blades, but it is true for Dance blades too.)
In that sense, I actually like the Ultima blades better.
FWIIW, almost all of the highest end world class Ice Dance skaters use MK Dance, though it is possible MK gives them blades for free.