The Nissan has R134 refrigerant - easier to find and cheaper
The Nissan has OBD1 or some kind of ECM troubleshooting "help" - if its a a '96 it might be OBDII...not that we like computers, but I do like ones that tell me where to start.
The Nissan is a newer car, the likelihood of obscure plastic parts failing is less
The Nissan has a timing belt? - (advantage MB)
The Nissan has a 5spd - one less hydraulic-mechanical system to break.

I'd forget a bargain-basement 190D if you have a '96 Nissan already. Stick with the newer hardware and the devil you know.

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2009 Kia Sedona
2009 Honda Odyssey EX-L
12006 Jetta Pumpe Duse
(insert Mercedes here)

Husband, Father, sometimes friend =)