I have one of each of those from previous offerings.
I first got the clamp version as I wasn't sure the surface of my desk would be smooth enough for the vacuum base version. I soon got annoyed at being limited to working at the edge of my desk.
The next time around, I got the vacuum base version - and was very happy to find that, with just a little water on the suction pad, gripped my desk very nicely.
I've used these for light mechanical work as well as holding some items firmly and at "just the right angle" for soldering. Something which can be especially useful for soldering multicore cable to pins of a connector.