Build quality and customer service - hands down SE846 is superior. JH and AK are still confused as to who deals with warranties on the Siren universal series.
Features - equal because you have base tuning on the Rosie and 3 sound filters on the SE846
Sound - purely a preference. If you want deeper sub bass, lush mids, and laid back highs go SE846. If you want more balance with a touch of mid warmth go Rosie. SE846 is one of the most sensitive IEMs and will result is some amount of background hiss except for higher end amps and DACs.
Price - same, but Rosie includes balanced cable and SE846 does not
Comfort - same, but the major difference if fit design means some will only find comfort in one but not the other. Personally, I could not get SE846 to fit comfortably, but the JH designs fit nearly as well as customs.