I've been using this for 6 years and it's just now starting to show some wear:

[Link: ridgid.com]

It's nice because you can stand on it, sit on it, and it's rectangular and stores the hose & cord inside so doesn't take up that much room in the van and you can stack stuff on top of it.

Round shop vacs always take up way too much space... especially with the hose.

I've been tempted to get something battery operated, but haven't done it yet.