Having now done both, I would take Dubai with kids full stop.
Recent trip with the grandkids and EK. Dubai was so good for the little ones under 10 that we stayed there for 5 days on the way back. So much to see and do.
When QF started going through Singapore it was illegal to spit and chew gum there. Plenty of bogan Aussies survived.
Dubai was an eye opener. Plenty of scantily clad tourists roaming the beaches, and being an old timer with the family in tow, I didn't get to stay out past 10pm, however what I saw made me realise the night life over there is, to say the least, a bit more exciting than most places.
Got to say I was rather surprised.