I'd lob them but what do you do if they are positioned not really close to the net? Passing them would be easier except its skidding, it that case I would try to hit a dipping topspin at their feet but that's still hard because its so low isn't it?
I voted lob, and I'd still do it 90% of the time. The only exception is when 1) I'm not reaching and digging the ball upwards, and 2) I'm early and stepping forward on the forehand - then I will probably will go for a dinking/looping slow topspin pass, either side if they're not too close to the net, to their backhand if they're getting closer (if they're on top of the net, then back to lob!).
The idea is not so much to make the pass, but to make them play a volley upwards. It means I don't have to inject too much pace to make the ball dip fast. Too much pace can mean it goes out, or it's still high enough for them to volley it away, or even if it's already dipping the ball has enough pace for them to just get their racket under it and bounce the ball softly over the net. So, slow enough to make them have to do something - keep moving forward, and actually hit the ball - to get it over the net.
I play a lot of doubles, so I practice a lot hitting groundies to volleyers and volleying myself. When I want to stretch the guy at the the net this is the shot I play most, and conversely when I'm at the net this is the shot that forces me to work hardest in terms of getting forward and down and then getting a good placement.
