I might be in the minority here, but for those of us for whom travelling in Suites is the exception rather than the rule, the daytime flight for me. I took the later SQ 318 as I wanted to enjoy the experience, food, wines, etc and arrive in London so I can make it home to sleep with minimal jetlag. I would have got less 'value' by sleeping for 70% of the flight.
If I was taking a paid flight overnight i'd probably downgrade myself to Business on SQ.
The 1am (SQ 306) I think is a 77W - will that make any difference to quality of experience (I don't know - only taken Suites on A380)?