Personally I prefer SQ over CX cos SQ has a wider range of
service throughout the flight eg warm towels.
In terms of inflight entertainment, CX didn't have on-demand movie
facility so it was rather boring having to wait for a cycle to end
so that the new movie will be screened. I prefer an on-demand
facility so that you can pause anytime or watch a new movie without
wasting time.
In terms of seating comfort, I find CX a tad crampier than SQ.
Wasn't an enjoyable flight at all.
I must say that the professional service rendered by the flight
attendants were very good at least. Same, if not better than
SQ.
The foregoing views are based on my experience on the economy
flights. 
