I noticed today that the AA use Vivaros and Trafics.
They're not going to choose an unreliable van are they?
Use your loaf. :
The Post Office use Iveco's......I would'nt buy one of those!
As as another poster already mentioned - theres a world of difference between running a brand spanky new one and a five year old van.
The Post Office, AA, RAC and big courier firms will get enormous discounts when buying vans in the hundreds and I'm sure Vauxhall, Iveco, Ford and the like all try very hard to secure those contracts so what 'sweeteners' they chuck into the deal well never know (longer warranties, free vans for breakdowns etc. etc.)
I've rented a Vivaro for a weekend and thought it was horrible. It was terribly slow and a little bit skittish for such a small van....but its the best looking van by far.
Personally my money would go to Transit. Easy for parts, every mechanic knows how to work on them. Lots in the scrappers for cheap bits and bobs and an impeccable record for realibility.