Please do a search on this forum:  this has been asked many times.

Its ford because they have been making the e series van for nearly 30 years so they know a lot abut vans. I saw a ford transit with 225000 miles and it still drove like brand new. 

Check this out

https://carkiller.com/scottykilmer/qa/ram-promaster-city-vs-ford-transit-connect-vs-nissan-nv200/

Here's my ranking:

1. Ford E Series

2. GM vans(Chevy Express and GMC Savana)

3. Mercedes Sprinter (diesel engine)

4. Ford Transit

5. Nissan NV200

6. Ram Promaster

I think the Ford E Series and GM vans are fairly reliable. Ram Promaster is basically a Fiat Ducato. Nissan NV200 is basically an underrated vehicle because I haven't seen anyone I know who owns Nissan NV200s. I only see the same 2 Nissan NV200s many times in the neighborhood. Mercedes Sprinter are fairly decent with the diesel engine, but it includes a lot of maintenance as they age.

I had a 2001 Chevy express van and the thing would not die no matter what I did to it. Ended up having 320,000 miles on it before I sold it. And that was on original motor and tranny. I don't know what GM did, but the thing ran like a clock.

For me it would be a tie between the Ford Transit, Chevrolet Express, and GMC Savanna. If you are going used them my number one would be the Ford Econoline.

i've had good luck with the ford E series, conversion vans. new, i'd lean towards a GMC as the parts are readily available as opposed to the Nissan or M/B

The first three are better