Out of the three options, the Tata Safari is the one to go for, for its excellent ride comfort, both on the highway and in urban conditions. It feels tough, and flattens bad roads very nicely. 

Moreover, it is more comfortable in all three rows than the Mahindra Scorpio N. Tata's 2.0-litre diesel engine is punchy, although the Mahindra car has an edge in terms of refinement.

The Force Gurkha is the most rugged of the three, and the most capable off-road. But since you want a car for on-road driving, it is also the least comfortable, feels utilitarian, its diesel engine lacks performance, and there is a lot more body roll than the other two cars.

For your 500km monthly journey and once a fortnight over 100 kms drive, you can go for either Mahindra XUV 7XO or Scorpipo N Diesel. 

They are great long distance car, excellent highway manners and matching performance. I must tell you, Mahindra is launching the updated XUV 7XO on January 5th and the Scorpio-N update is expected sometime early next year. 

Keeping that in mind, we suggest you wait. If you want to go for the current models, you can negotiate with the dealer for a better price. 
 

We think you can wait for the Mahindra XUV7XO launch. Since this is a facelift and not an all-new model, some of the initial issues that customers often face with fresh launches may not be present. 
Tata Harrier has some ergonomic concerns, and with your height, you may find it difficult to settle into a comfortable driving position on long journeys. If teething issues with the XUV7XO facelift are a concern, the Mahindra Scorpio-N is a sensible alternative to consider.
 

The Mahindra Scorpio N is a tough, dependable SUV built to handle rough terrain with ease. 

Its body‑on‑frame construction gives it the strength to handle rough roads and punishing conditions. Prices start at around Rs 16 lakh and go up to about Rs 28 lakh for the top‑spec Z8L variant. 

You can choose between powerful petrol and diesel engines. But if you plan to buy one, the 2.2‑litre diesel remains the better option for its strong torque and efficiency. Unlike the older Mahindra Scorpio Classic, which continues to be on sale. The new Scorpio N has a forward‑facing third row and a cabin that feels hard‑wearing yet well-equipped. 

The ride quality can get a bit choppy on uneven surfaces, and it does lean through corners, but overall, it’s a solid, go‑anywhere SUV that’s built to last.
 

The Mahindra Scorpio N is a ladder-frame SUV, meaning the body is bolted onto a chassis. This construction makes it more hardy, however, the Scorpio N will have that typical body sway that is associated with chassis vehicles. 

The ride is thus not settled over undulations, and this is where the Mahindra XUV700 is better. It utilizes a monocoque construction, which is where all components are bolted to the body shell itself. This gives the car overall better rigidity, resulting in better ride and handling, something that is noticeably better with the XUV700. 

Engine refinement and performance are similar, given that the two SUVs share the same powertrains. However, real-world efficiency is better with the XUV700 as it has active safety. Also, the XUV700 has better and more stable handling at higher speeds.            

For your requirements, the Mahindra Scorpio-N 2WD Diesel 2.2L Turbo Automatic 7 STR Carbon Edition will be the best choice. It has more power and torque than the Tata Safari. It also has a more refined and stronger-performing diesel engine, a smooth-shifting automatic gearbox, and the Carbon edition has an aggressive look as well. 

It has one of the strongest road presence in India and is very well off the tarmac and over bad roads.