I'm super new to ducks, and I only have experience with Cayugas (3, 2 girls and 1 drake), but I thought I'd do my best to answer with what I know, I hope it's helpful
Most of what I've read has said it's best to have 3-4 girls per drake. I got my Cayugas sexed as all girls but I guess there was a mistake, I'm planning to get two Welsh Harlequin girls in May to try to make sure I've got enough, and It's an excuse to get two new ducklings
My drake is quiet, I think all drakes are. With the girls, they're capable of being very loud if they want to, but it's very rare, they had a period where they "yelled" a lot but it was only when they wanted something, like company or food, now they barely ever raise their voices much, they chatter a lot but it's not loud at all.
Mine are only just reaching maturity, they haven't started breeding, so I don't know anything about it from experience, but I've heard quite a few stories of people's drakes becoming complete jerks during breeding season, becoming aggressive towards other ducks and people, biting, stuff like that, I don't know how common it is, but it is something you may want to be aware of.
For personality, mine aren't fully tame, so I can't really talk about their friendliness, they eat out of my hand, the drake doesn't like to, he keeps his distance usually, but he's willing to. The girls come right up to me for treats and eat out of my hand, they've even done it while I had a cat on my lap, haha. I'm working on socializing them more now, and they are slowly getting more comfortable with me, the drake, while also being the most shy, for some reason accepts being held for the longest, he doesn't like it, but he tolerates it without too much struggle.
They do scratch me, but it's only when they struggle about being picked up, I think as long as you made sure yours are well tamed and used to it, it shouldn't be an issue. They nibble and bite sometimes but it's literally never hurt, it's been slightly uncomfortable, but never pain.
I'm getting Welsh Harlequins mostly because I've heard such positive things about their personalities, people saying they're very friendly. So just based on what I've heard they'd sound like the better choice. A mixed flock could be very nice. Cayuga drakes are gorgeous so if looks matter, my boy has such a bright green head and pretty colours all throughout him
Good luck! If you've got any questions I'll do my best to answer, hopefully you'll have more experienced people reply though.