It's a two-stage decision. First you have to decide if you're going to play riskier and more aggressive by taking it on the rise or drop back to take the ball as it's descending in the arc. Then, you have to decide slice or topspin. This will usually default to which shot you're more confident hitting.
I personally will take the ball on the rise and drive it with a little topspin if I have time (I tend to play more aggressive). If I have to track the ball down and catch it late in the bounce then I will usually slice it hard and downward to keep it low. This is because the guys that I usually play will always attack when they know they've got me pinned deep. I can't afford to float a slice deep because they'll just come in and put away the volley. I have to get the ball down to their feet.