What Would Be Better For A Rottweiler A Crate Or A Pen?

I would say that depends on what goal you are trying to accomplish.  If you simply need to keep your dog confined and you are able to keep him or her outside (or if you need something that you can leave your dog in for an extended period of time), then the pen is probably better.  However, if you plan on housebreaking your dog so it can live in doors with you, then the crate is a better option.  You can begin leaving him or her in the crate for a few hours at a time, and this will help train your puppy to hold its "need."  We also used the crate method for our female rottweiler for the first few years of her life to let her get over her "destructive period." We'd crate her when we weren't at home and sometimes at night, but we have little need for it anymore.

If you choose to use the crate method, I suggest a couple of things.  I would go ahead and buy the extra large crate while s/he's a puppy - this will save you money in the long run because you shouldn't need to buy another one when he/she gets older.  S/he's going to grow pretty quickly and s/he'll need enough space to stand up and turn around comfortably as an adult.  Some rottweilers can take several years to mature out of their puppy mentality, so you could end up getting a whole lot more use from the crate than you initially thought you would.  BUT - you will need to put something in the crate to take up some of the space while s/he is still small in size.  Dogs usually will not go to the bathroom in the same place they sleep, so you should block off the rest of the space in the crate except for a space just big enough for him or her to lie down comfortably.  As s/he grows, just take some stuff out of her crate to allow him/her more room.  After a couple of months, s/he will begin to recognize the crate as his/her own space.  I 'd start out with putting a soft blanket in the bottom of the crate - just make sure its easy to wash - and then replace it with a nice bed when s/he gets accustomed to holding it while in the crate.