Timothy is the best, or at least most recommended for pet owners.
Alfalfa is to be avoided for the most part unless their environment is cold, as it causes their body heat to jump.
I know that red clover is a problem for some ruminants, especially pregnant ones, but I never got a straight
answer as to if this applies to rabbits.
My rabbit, a Flemish Giant named Mizzou, will eat a sunflower plant down to whatever is left above the soil line, though if it's three metres high, it might take her a bit. I would see if that works, along with other plants they will eat. I wonder how
nettles would go over...
Incidentally, one of the first things I read when researching rabbit ownership was that there was a distinct difference in raising a pet versus raising a meat rabbit, even if coming from the same litter. Apparently, it is desireable to limit the amount of protein the rabbit gets if you intend it to live a long time as a pet. Someone raising rabbits for meat has no such considerations, and frankly wants as much weight gain and growth as is healthy for the breed in as short an amount of time as possible. Meat rabbits don't need longevity.
So Timothy is best for pets, I think, but in cooler climates, a mix including alfalfa might be better for meat rabbits.
-CK
A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects.
-Robert A. Heinlein