Guineas are still "wild fowl". You can tame them; but, it takes a ton of hard work. Daily handling at least twice a day for several minutes at a time. You can keep them with other fowl, if they have been raised with them and consider them part of their flock AND have plenty of space. Most people don't recommend it.
The second a guinea feels confined, they get mean. It's not because they are mean birds - it's because they feel trapped. They still have many of the wild instincts and when you confine a flighty bird like that, you can expect repercussions. With plenty of space, they do fine.
They are LOUD...there's no getting around it. Personally, I like the sound of guineas. A lot of people don't. I also do not try to treat my guineas as pets. They are more like the rescue birds and reptiles I've taken in. I handle them only as much as necessary, and do everything I can to make them realize I'm not a threat. I move slowly, don't chase them, and give them plenty of warning of where I'm going. I get in - do what I need to do - and get out. Their space is exactly that - their space. They tolerate me while I'm there; but, they are much more happy when I'm out of their territory.
Guineas do eat ticks...which is a huge plus for me, given my location. For me, though, the biggest benefit was my husband's happiness at having them. He used to have them as a child and still carries that fondness for them to this day. I think they are ugly - but, I love their 'song', the eggs are good and they keep me tick free.
Between my chickens and my guineas, I've hardly any pests to worry about on the property.
I've never had ducks, so I can't speak about their behaviors or personalities.
