The ONLY reason to even consider the Sheraton, IMO, is because the OP is SPG PLT and thus might get some sick upgrade. That's not guaranteed, of course.
Otherwise, this (to me) is a no-brainer in favour of the Conrad. Better hotel, much better neighbourhood, better location for kid-friendly activities (backs to HK Park, walk to Peak Tram, most 'touristy' stuff is closer to Central/Queensway than to Kowloon.)