Those are some cute birds!  A flock of two, hey?  Are you planning on getting some more?  If it's not too personal, what happened to the other three to cause their demise?  (Just trying to learn and avoid possible trouble!)
 
My RIR's are definitely more aggressive than the Buff Orpingtons.  We bought all of our chickens at a poultry auction on the same day. The 3 BO's were in one cage, and the 4 RIR's had been raised together too.  At first, no-one wanted to mingle.  When they did, the RIR's were very pecky with the BO's.  Not to the point where any feathers were lost though.  I think they were trying to establish their pecking order, and the RIR's came out on top.  They sleep on the top roost, even over our cockerel George!
 
The RIR's are fine to work around but hard to catch!  If anything, they will run away when I come near them, whereas the BO's like to follow me around, and come running when they see me.  I have heard that RIR roosters are a force to be reckoned with though 
 
 
I guess it depends on what you are looking for. I got the BO's because they go broody, and I thought I would be able to add to my flock with them.  The RIR's I got because they rarely go broody, but are good in the egg producing department.  When the other 3 start laying I'll let you know!
 
I like them all, but I love the BO's nature. They are very funny and so sweet, I would recommend them to anyone.  I would like to get a couple more birds to add to the flock but am wary of introducing pests (mites, lice, worms etc) and causing upset for my current birds.  If I do add to the flock, I would like to get a couple of Australorps and a couple of Wyandottes.  I will have to see how I go convincing hubby to buy me some more!
 
Krista.