Daily budget is a way to ensure that the traffic is steady and more distributed, when you are running a longer campaign.
My opinion is that lumpy traffic is better than spread out. Lumpy means that there will be times with more traffic and times with less traffic. Lumpy is good because it means players will be more likely to have other players to play with. Also lumpy means that you might have more efficient spending with low bids.
If you already have a successful game or if you are trying to keep a sustained player count over the course of days, then you’d want to use daily budget approach.