Rare Dankness makes some interesting crosses with Bubba in them. Personally, I'm considering the Grape OX, but there is also Blue OX and Cornbread Bubba as well.
Also look into CSI Humbolt Purple Urkle and/or it's crosses. Burkle should be a good one.
Can't go wrong with straight Bubba either, but personally, I prefer it crossed with something on the fruity side.