I have Muscovies, a Pekin, an Indian Runner, and Pekin/Runner crosses, so I'm going to stick to the breeds with which I've had personal experience. If you're looking for a mellow, docile breed, I have to recommend Pekin. They're also pretty good layers. Runners are good layers, too, but mine are a bit skittish (I got the Runner as an adult)...I do think they could be more people-friendly if you start at an early age. I find both the Pekins and Runners to be good foragers, and neither fly well. I think either/both would be good for new duck raisers.
Muscovies are great birds, and very unique - excellent foragers and broodies, but mine have retained their "wild" nature. They can fly well and the drakes are large and powerful - even the ducks, which are smaller, need to be handled carefully because they have strong feet and claws. Muscovies don't lay as many eggs as Pekins or Runners, but they are unequalled when it comes to hatching eggs...and not just their own. I consider them to be best suited to "intermediate" duck raisers.
With the Pekins and Runners, I doubt they could get over a 4' fence (not true of Muscovies, though, so I clip wings). While they exercise their wings, I've never actually seen my Pekin, Runner, or the crosses get aloft. My ducks all get along with my chickens and while they are in separate coops at night, they all free range together during daylight hours.
I'm sure other BYCers will opine, too. There are many great choices - I hope you enjoy your duck-raising adventure!