
Combo>Ponder. Lets you see the most amount of cards possible(up to four) while giving you the best ability to set up.
Control>Preordain. Lets you see less cards, but gives you the best digging ability and information.
Tempo>Ponder/brainstorm. Ponder lets you set up your delvers(biggest incentive to play tempo) and brainstorm is an instant.
Brainstorm. Fine, though unexciting card without shuffle affects. Broken with shuffle affects. If your deck has no way to shuffle itself, I'd pick another cantrip first as brainstorm locking yourself is a very real way to lose and then tilt.