I've never owned a transporter as they are overpriced as a workhorse and usually low spec - I've owned a VW polo and Scirroco both where just as reliable as any other brand car.
Had the use of vivario for about 6 months and found it a nice enough van. Slightly smaller than a SWB low roof transit.
My mercedes sprinter campervan has just died and finding anyone to look at it was the hard part. The recovery truck driver must have phoned about 30 garages, all busy when they heard it was a Mercedes Sprinter. Even my local mechanic once home pulled a funny face when I tried booking it in. But they are great vans when working.
Owned 3 transits and found the mk5's indestructible, the mk6 I owned spent just as much time in the garage as it did with me. In fact apart from the shell everything else had been replaced. I've been told the new Ford Adblue transits are terrible.
Currently driving a Renault Master but haven't had it long enough to draw any conclusions - seems ok despite the usual dont buy French recommendation.
Also owned an LDV Convoy & Maxus. The Convoy was old fashioned but bulletproof and the Maxus was probably the must reliable I've ever owned (apart from continuous clutch system faults). Think they have just started making the Maxus under a Chinese name but can see the depreciation being high.
I personally would try to test drive both and buy what you prefer to drive. There is more conversion fixtures tailored to VW transporters than other vans.
Post edited at 20:27