If you plan on driving the vehicle occasionally
If you go off road frequently then Prado but only if you find one in neat condition. Do not go for an average car because maintaining a 20 year old vehicle will be difficult. try to get a Petrol ( preferably 3.4) variant car as 1kd diesel is a headache to maintain.
If its going to be a daily driven car with no or minimal off roading then Oshan because Brand new car will be peace of mind for atleast 5 years plus it comes with a lot of extra features.
The cross overs marketed as SUVs are lemons when it comes to 4x4 capabilities.
Also Oshan is a not a true 7 seater as 3rd row space is less as compared to Prado.