MasterLow is one I can think of.
There are other crosses but some won't autoflower.
Read a report that when crossing LR (which the autoflowers out there are crossed with LR, ruderalis trait) have only a 25% chance of autoflowering.
Best thing to do is lurk around forums and grow journals to see what peeps are saying about each cross. Mainly all I see is LR and LR2