Big decision

it would probably be better IMO to get one first and the other 3 - 6 months later. This way you will have bonded better. If you get them both at the same time, chances are they will bond with each other better than with you unless you spend oddles of time with both of them seperatly. However, if you dont spend the time needed you wont bond properly with either of them regardless.
 
Welcome by the way

For first-time two-dog households, do NOT get littermates.  I'd also suggest opposite genders.
How much experience do you have with both breeds?

Multiple dog households have their good points and bad points.  As to those breeds, sure you can have to IF you do adequate training.  In most cases (this is based on my experience of being the instructor in dog training classes for the general public) you need at least a year (4-5 sessions) with active homework and socialization to be able to adequately train a large and powerful dog.  The issue that has not been addressed, is dogs feeding off the emotional energy of each other.  Whatever negative behaviors will be magnified.  Having one dog very well trained before the other comes, will increase the good points of owning multipe dogs and give you the support of a well trained dog as a model.  Dogs will learn from the other animals in their environment so this way you have an extra pair of paws for training.  Mixing the genders is also a good idea PROVIDED the dogs are spayed and/or neutered.

But i've read alotta articles and some ar like go for it. But others suggest that it will go alot better if i get one then train him and then get the other one later

In addition to reading articles that state do or don't are you familiar with either of the breeds in which you would like to have?
First read up on these very diffirent breeds.
I do know about Pit Bulls and am educated on their needs, likes and dislikes. I do know you cannot have two free roaming the home while you are not there. Crates, are a wonderful thing.
I would say do some more research before getting two of what ever breed you decide on before just getting them.
 

Yes i've been around both breeds extensively.  I have never owned one.  I have owned a 30 pound rat terrior and been through two sessions of classes. One of my best friends has 3 pitbulls and i am around them almost daily i have helped him train his last 2 and watch them for him when he's out of town.  I also have a friend with a rottie and am around him often and help him train. So the breed and training isn't a problem it's jus the order that i get them.

Make sure if you want to get 2 pit bulls that opposite sexes would be way better......also, adopting adults would be preferable since dog/dog aggression
might not show up till the dog is 18 months or so.
As far as the rotties go I am no expert on them but good luck!