I do both, the evenings are going to be more predictable, the hogs ARE going to get up and go eat. Just have to find them before dark so shooting time is limited.
Mornings are the funnest if they are moving because they become unpredictable and can be out until 10 am sometimes, but also most are bedded before sun up. Depends on the property and the weather, a little rain and they tend to be out feeding late.
Just like Jesus, sometimes you gotta kill some hogs.