An ferrite bead works well too, is easier to design in and I suspect it has less losses than a snubber. Just make sure the ferrite bead is choosen well when it comes to the frequency response.
+1 this, but with caveat:
You may very well be at high enough power level that you get a Metcal tip rather than an EMI bead.
That is to say, the ferrite bead's losses (to your circuit, it's basically a saturating L || R) are high enough that its temperature rises to Tc (Curie temperature), where L drops off, losses drop off, and it regulates its temperature. Meanwhile, your EMI spectrum looks good for the first few seconds of operation, then the spikes rise back up to normal levels. A hot ferrite bead is a useless ferrite bead.
Solution: either reduce loop inductance, increase commutation time (losses go up), or snub the loop inductance. Which, since reduction is the first priority and you're unable to do that, you now have to increase it, by adding an inductor (not a ferrite bead -- inductors saturate at rated current, ferrite beads saturate at far less!), and damping or clamping that.
Also, have you done the dance with the Y caps? Sometimes you want one pri-sec or pri-GND, other times you want as little as possible. Depends on the exact windup of the transformer, and whatever else is farting out noise (heatsink capacitances, proximity, etc.). I always put in all combinations, in the PCB design, then try permutations until I've found the minimal set and values.
Assuming, of course, a traditional PFC --> converter design. If N/A, then YMMV.
I suppose if things are very compact, you could also have induction into the supposed-to-be-filtered side, which can really only be solved by reducing loop areas (use 2+ layer construction??) or making it bigger (getting the filtered side away from the noisy side).
Tim