Everyone has their favorite way of entering sweepstakes, and there is no one method that always works best. If you have the time to enter often, you have better odds of winning daily sweepstakes than of winning one-entry sweepstakes. After all, most people who enter won't enter every day. If you do, your odds will be better.
That being said, entering daily does take a lot of time. If a sweepstake runs for a month, you could have entered 30 other sweepstakes in the time you spent entering a daily sweep every day.
So my best advice is to split your time between the two types of sweepstakes. Pick as many daily sweepstakes as you can reasonably enter every day, focusing on the prizes you most want to win.
Spend the rest of your time each day entering one-time sweepstakes, so that you get a wide variety of chances to win.
Also, don't be afraid to enter daily sweepstakes even if they are close to their end date, or you only have time to enter once. While the odds of winning dailies are higher if you enter every day, it only takes one entry to win. If you don't enter at all, your chance of winning won't only be long, they will be non-existent.