I've got a couple of Croft soft crates:
http://www.croftonline.co.uk/mcp/Soft_fabric_dog_crates.htmlI've got a Twist Tent - very light and folds very flat, however, if you've got a dog that likes to throw themselves against the side of the cage, the cage will roll! My girls are fine, but one of the lads gets bit spooked by his world suddently turning upside down! It's got a lightweight metal frame, allowing you to twist and fold it closed.
Also got the Tube Framed soft crate - tube all around so much more rigid. Doesn't pack down as flat as the Twist Tent, but is much more substantial whilst still being easily transportable.
I am pondering getting the Fabrikennel, something between the 2.
As someone else has said, if you've got a chewer don't bother ... the Argos metal crate is quite light (compared to other metal crates) if that's the case, nor any good if you've got a heavy floor digger!!