Isb registered old SUV's have very low Token tax, maybe something to do with date of registration and it should be around 500-600.
Diesel vs Petrol - depends upon proposed usage (On/Off Road, Weekend Toy/Daily Drive, Availability of Good Mechanic etc.). Kms/L are usually higher in Diesel unless its highway driving. Diesel noise will make it to the cabin in Gen 1.
To enjoy SUV ownership, you should get vehicles inspected by a reputable SUV mechanic and get a full report (something like PakWheels CarSure report) and then take a decision. Do not use any road side mechanic for this, find a person who knows the respective brand and has a few for repair at his workshop. SUV can prove to be a money pit if not pre-inspected properly.