G'day Doogle, there are pro's and cons for both and I have had both.
My personals experiances are,
Wind up ones do take a little longer to set up but can be a bit more versatile if the ground is uneven. The foot print of the leg is smaller to so I would recommend getting some ''Leg Treads'' which is also handy if the ground is soft. Also the thread on the adjusting bolt needs to be kept clean so the thread doesnt get damaged but that really is part of regular van maintenance anyway and never posed a problem I use to clean the thread with WD40 because dirt doesnt stick to it like grease and we travelled alot of dirt roads too.
The drop jacks a quicker as they drop down close to the ground and only have to be wound down a small way and are wound down from the side of the van rather than from the front or rear of the van like the wind down. They do seem to be a bit more stable as the box section goes all the way to the ground and it double skinned to a degree if that makes sense because the inner winds out when lowering. I haven't had to set the Expanda up yet on a very angled site yet so I'm not to sure how they would go then as they have to lock in for them to work before they can be wound down. As for the foot print the 'Leg Tread'' is std on a drop down. Personally I think the drop downs are a bit more stable. They still do need maintenance on the thread and the handle that locks the leg into place, I have heard of people breaking the locking handle when trying to release the stabliser.
I think I prefer the drop down as they are a bit quicker but to tell you the truth I was also happy with the wind down as they worked well and were a bit more versitile on uneven ground.
I hope this hasn't confused you to much
Cheers Cruza