I think 6 upped sundials is best, if you have them. They do give you the occasional towerless hand, but being short on time quanta can be a problem even with fully upped cards, so you want to save on it where you can.
If shard of bravery comes out in its current form, I'd ditch all of the hourglasses and sundials, and use shard of bravery and precogs; you'll win by like turn 4-5 almost every time. Your win percentage with that would probably be over 90%, and with luck a first turn kill would be possible.