No, they're not the best. But then they don't cost USD 30 each, either. Nice find on the CDCS502---most datasheets don't have a phase noise spec so it's difficult to reason about whether they'd perform better or worse than the XpressOs. At the lower cost end of the range the overall jitter figures on competing parts are higher, sometimes significantly so, and some parts don't even have jitter specs. For example, the CDCS502 datasheet states 100ps cycle to cycle jitter. But not the measurement conditions or whether that figure is peak cycle to cycle or some other metric. If one assumes it's peak cycle to cycle it's probably reasonable to compare it to the XpressOs' total jitter figure of 26ps. In which case the CDCS502 may result in worse performance than the XpressOs despite its lower level of phase jitter. It's been quite a while since I had access to a jitter scope so sampling the two parts and taking measurements to enable direct comparison unfortunately isn't really an option for me.
My experience in ambiguous situations such as this is parts with more complete characterization information in the datasheet tend to work better. That's just a rule of thumb though.