Which breed is most compatible with Rottweilers

Question
Hi, I have a 6 year old rottweiler. Do you know what type of dog would be the most compatible? Also, since my rott is 6 yrs old now, is this the right time to incorporate a new pup to the mix? My boyfriend and I were thinking about another rott, a lab, or a great dane. We like med-large size dogs but are open to suggestions. Please let me know if you need more info. Thanks for the help.  

Answer
A lab a rottie or a great dane would all be good choices,and it would be best to get a puppy-as adult dogs don't feel intimated by it,and the new dog will just grow up with your current dog

SOME great danes can be dog aggressive,but not all are,and a pup again would be the best bet

so go with the breed you like the best