Hi,
I cant help with Dobs but have some experience with Mals.
We have 3, our eldest being 5. I would say you have to make one hell of a commitment when you decide to get a Mal, they are more of a lifestyle change lol Like our friends and family will say 'I can't remember a time before Mals now'.
They are a lot of hard work, but if you are willing to put the work in they are a joy to own, and one is never enough!! Puppy training and socialisation is a must. Mals
can be dog aggressive, due to their dominant nature, but with good socialisation that doesn't have to be the case. Ours are ok with our 2 terrier crosses, and they are a tenth of the size of them. Ours boys especially are great with the small dogs, the girl can be a bit grumpy, she likes her own space. I would say they learn quite fast, if there is something in it for them

They are very stubborn!
Another things is the hair, when they shed their undercoat (twice a year, but you will find hair around pretty much all of the time) you can get bag upon bag of fur out of them. The garden, they love to dig, very much so! Ours are past that stage now, but when growing up they dug, A LOT. We have 2 gardens, one for them and one for us! lol
Ours don't go off the lead, I know others who do let their Mals off but they are known to have poor recall, and I'm just not brave enough!
I'm sure there is plenty more things I have forgotten, but I'm at work at the mo. It may sound like I am putting you off, but really I am not. They are wonderful dogs, and I know I will always have one in my life, but you MUST be prepared to put in the work, it's so worth it if you do
Here are a few pics...
First, THE HAIR, this was a 10 minute brush, and he's barely moulting at the mo lol
The big boy with his best friend