I have not noticed bunnies having any predilection for one hydrangea variety over another. I had to use a rabbit repellent spray to control things in front of the house; a fence and dogs kept the other parts of the house free of rabbits. Ironically, I even protected an area in the side of the house from the dogs because the bunnies had babies in there.

Although you probably can't keep up with propagation rates of the bunnies, you might want to try and eliminate nesting/burrowing sites around the property, throw nets over shurbs in winter. Spray liquid fence low to the ground.

Or, if you have "relaxation" time, buy almost any pneumatic or CO2 air rifle/pistol. Most BB's traveling at 400+ fps will actually stun most rabbits to death. No mess, just dead rabbits. Simply bag them up with your weekly garbage (or use whatever other disposal method you can think of). It sounds macabre, but works. And I'm no meanie; the bunnies around my place have left most things alone, so I'm at the stage where I'm walking around petting the babies that hide around my foundation walls.

(Note: do not use air pistols on much else but rabbits unless you simply want to stun things like deer. Squirrels and ground hogs, for example will require the use of live ammo such as .22)