I would go with the buck (male). When does (females) reach breeding age they can get very territorial, which can lead to aggressive behavior that includes bitng and scratching. The bucks are usually much more laid back through their whole life.
A Holland Lop is the smallest of the Lop breeds in the US.
They only reach about 4 pounds when fully grown. Bucks and does of this breed are the same size when full grown.
I raised Hollands at one time and from my experience witht them the bucks are just more mellow than the does.
I have never had a rabbit altered before so I do not know at what age a vet will neuter. it should be done before they reach
"puberty". Sometimes a buck will begin to mark his territory when they each maturity (around 5-6 months in Hollands) so to avoid this behavior you would want to neuter him before he starts it.
A rabbit will only be as social as you teach it to be. The more they are around people and in situations the better they will learn to adapt to it. The more they are handled and cared for the tamer they become.
Always be careful with a rabbit around a dog or cat. Rabbit are prey animals and dogs and cats are predators. Even if your pet has never shown an type of predator behavior it could come out when presented with a situation. never leave them alone togehter, not even for a minute. That is all it takes for a predator to snap a rabbits neck and kill it. Also rough play of any type can lead to broken bones, and a rabbit with a broken back is not a pleasant sight.
Even if the pet does nothing to the rabbit it can become very scared and stressed by an unknown animal.
Make sure you have all the supplies you will need before you bring your rabbit home. A cage is a must it is your rabbit safe place. A litter box( a small one for this breed). Pelleted food, good grass hay and plenty of water(unchlorinated if at all possible) Rabbits need wood to chew on also as their teeth never stop growing. You can buy an untreated 2X4 at a home improvement store(Lowe or Home depot) they will even cut it for you. Cut it into 3 inch pieces.
Rabbits like toys to kep them busy. Mine like golf balls, kitty balls witha bell,cardboard tubes, pvc pipe pieces,plastic easter eggs, old phone books(to rip up).
Good luck with your new pet. You can check out the Holland Lop rabbit Club(s) by going to the ARBA website.
http://www.arba.net