I'd plump for the Disco.
The Jeep may be quieter, and possibly more comfortable, but you're talking about buying an 8-10 year old vehicle. The ongoing maintenance and parts costs are significantly different. Also your chance of getting hold of second hand parts for the Jeep are far less. Finally the Jeep Cherokee is not very big, whilst it will tow the same as the Disco you'll be surprised how little space (storage and boot) there is compared to the Disco.
I hope I'm not being biased in my reply, as I don't own a Disco but have owned 2 Cherokees, but sold them at 8 years sold because of the growing size of the repair bills.
Tazz