Which is the best shot against a spinner, sweep shot or a front footed drive?

a front-footed drive... it gets the foot forward, to the pitch of the ball and thus, the best defence against lbw, if the ball spins past the blade

The question should be more specific to the type of spin you are facing (to a RHB):

Leg Spin: The best thing to do here is to have quick feet and be able to get to the ball and make whatever ball is delivered a half-volley.

Off Spin: The sweet shot is great to use here as long as you take a long stride forward and keep your head over the ball. It is a good shot for negating the LBW and there is plenty of runs to be scored from it – just watch Hayden in the 2000— series in India.

Just take a leaf out of players such as Michael Clarke, Jaques Kallis or Michael Slater who are fantastic and playing spin bowling and have done so well on the sub-continent wickets against some of the spin bowling or pitches that are so conducive to spin bowling.