Most people will.buy a new van because of reliability.
But thats not really the case. The newer vans euro 6 have a lot of issues with dpfs. Theres the wet belt issues with ford's the chain issues with the Peugeots etc. When a newer van goes wrong its having to deal with warranty and a dealer and if you are just outside that and your engine blows it can be 5 grand or whatever.
Even if an older van costs you more in replaced wear an tear items like suspension, brakes etc and maybe a clutch and a starter and bits here and there it will always work out better than the massive depreciation you pay on a new van.
If the new van depreciates 15k over 5 years (it will be more) thats 3k a year that has to go wrong with the older van. Ive had about 10 or 15 vans and never had anything like that, you could replace the entire engine and gearbox every year for that and still beat the depreciation.
Depends though, I cant remember last time I went to a garage ive done clutches, injectors, cambelts and all the usual servicing stuff on my driveway. Only time I go to a garage is mot time.