The best rootstock to use will have multi branches. If you plan ahead you can prune to force the rootstock to branch out.
Heres a pic of the tree I made from Benny's Clemnule buds he sent me. Rootstock had three nice branches. I grafted a Clemnule to all three. I should have grafted another variety to the center branch for a polinizer...
Heres another I just budded up.