I prefer the evening. It feels extra nice to settle in at the cinema when the day's winding down. It also eliminates that moment where you step out of the auditorium with your insides feeling janky from too much popcorn, and emerge dazed and blinking into the sunlight like a troll coming out of its cave. Although that might be just me?
With regards to the atmosphere, I think with comedies it definitely helps. I've enjoyed a few comedies at the cinema that, without the crowd enthusiasm, I wouldn't have laughed at once. That happens a lot with action film quips as well, I find.
There's also those moments when an audience has been silent for the whole film, but then something happens that gets a reaction out of everyone. I know there's been a few of these, but the only one I can think of is in the Departed when Martin Sheen's character gets killed falling in slo-mo, and when DiCaprio gets shot and everyone in the audience made sad noises.