
And I'll second that. My dobe boy was my first dobe - and my first proper dog (after the family spaniel mix years ago) - and I wouldn't recommend a male to a first-timer. Remy isn't even typical of the breed - dobes as a rule are VERY energetic, whereas Remy is VERY lazy (and no medical problems to blame, he's just idle :D). He's still been very hard work - like many males he's got a stubborn streak a mile wide, and also like a lot of males he will not live with another male in the house. Visiting, neutered ones were fine last time I tried but not entire.
My girl is far more typical - she's 6 years old and still a puppy :D Very energetic, always on the go, although she does know when to settle if needs be. I won't say she's more biddable than Remy, but she wasn't trained or socialised properly before I took her on a year ago so I do have that disadvantage when interacting with her - there are trust issues that we're still working through.
But from what I learned before I got Remy, and since, bitches are a little more biddable. Males are far more goofy - Remy can be a complete fruit loop if he's having a funny five minutes! :p Definitely the clown of the two sexes. I've also read that bitches grow a brain at 2 years, and males at 3 - and that sounds about right to me. Lazy as he is, Rem did take a long time to mature.
Aggressiveness isn't something that should be present in any dobe - it's all down to the raising. My girl is fear-aggressive with other dogs, but that's entirely because she wasn't socialised as a pup so she is frightened of them. Remy was socialised thoroughly from day 1 and is very good with other dogs of either sex, it's only in the house that he gets grumpy with males. Bottom line is, if you're willing to put the work in then you'll have a lovely dog regardless of sex!