Note that there are some sleeper service flights, which gives lesser service. Depends if you want to enjoy the service, then day flights would be better.
I for one, would prefer day flights as I cant really sleep on the plane, prefer to sleep on proper bed.
Personal preference I guess. As I usually shuttle between the States and back, I've grown to be used to sleeping on a plane. The F/R products on SQ are perfectly fine for me to catch up to 8 hours of sleep at once. Their J products are decent, although I really dislike the new J seats on their A359s due to the small foot cubby. As a result I will prefer redeye flights as flying on a day flight will mean adding 2 more days to my trips.
I guess if you're taking the flight to 'experience' the F/J products then sure go for a day flight, as some sleeper services don't offer the full F meal. After this much flying, I don't see an F meal to be special anymore, and any decent restaurant beats any airline meal hands down.