what would be the best option ?

[Maddiesmum]

One thing to bear in mind about cat friendly dogs.  They may be friendly with the cats they used to live with but this doesn't necessarily mean they are friendly with all cats.

[Den]

Cat friendly rescue for sure. Puppies may be cute but they are annoying, something which your cats probably won't appreciate. There is no guarantee either that the puppy will grow up liking cats. Also, puppies are into everything and everyone whereas a cat friendly rescue will likely ignore the cats which makes it easier for the cats to adjust 

Editing: Feel my answer is too short and simple 

There are countless puppies in rescue, many brought up around cats, dogs and children. So finding a cat friendly puppy is easy. It might well come down to what you want ... a puppy/adult/oldie. The fact your cats have previously lived with dogs is a good sign they will be ok after a bit of readjustment.

[purrdy]

Hi
we are wanting to adopt a rescue dog (must be a cat friendly one)
our cats lived happily for four years with our last dog until he died 
obviously the cats come first and we will not do anything to upset them at all
and i was wondering what would be easiier for them to adjust to
a rescue dog (who was used to cats)
or a puppy ?