AM is definitely better, I read some research confirming that but I don't remember where....
PM might lead to difficult sleep too (in my experience it depends...).
Thing is optimal would be taking a nap after weight lifting....not everybody can do that AM.
Weight lifting on an empty stomach isn't going to be very productive, generally speaking at least.
A proper meal is needed in order to optimize power output, likely not everybody can afford a proper meal before training AM.
Ideally meals should be around training time, a big one afterwards is again something not always easy AM.
A big carbs rich meal after training heavy leaves you willing to nap, not to get active...again AM usually isn't the right time for that.
OK, lets skip the meal before and the meal after and the nap....yes, but now I am not so sure anymore that training AM would be so much better.