Anyway...if you're considering a rottie...
They're a bit livelier than labs (I've had labs before) same sort of activity levels, but just a bit more full on about everything they do.
Different to train as well, they're not as biddable, so they don't come wanting to please you, they do things for the reward - which does mean if what they want to do is more rewarding than what you're offering then they'll go and do that.
Once you've got a good bond with them though, they're hugely attuned to you - they're also quite sensitive, don't react well at all to harsh training methods or even you losing your temper.
I genuinely think that a lot of the bad press around rotties comes from the fallout of shitty training methods, I can't imagine them turning out OK with owners who do things like alpha rolling.
They're a huge amount of fun, just complete silly clowns, but really clever (in a training sense) so mine can pick up a new command in about an hour...but can't work out how to turn round in my kitchen so has to slowly back out instead, lol.
They do absolutely everything with full enthusiasm levels, games, training, playing, saying hello...
Much lower shedding than a lab and they usually don't bark much, but they have all sorts of other noises, they quite often rumble when they like where you're stroking them for instance.
Very affectionate and have no clue that they're large dogs, they genuinely think they're lap dogs and see no reason why they shouldn't be sat on your knee giving you kisses 
But, you do need to be very careful where you get them as there are loads of dodgy breeders and with the health issues they're prone to you can't be too careful...oh and insurance is ridiculously expensive for them.