Choosing a 4x4 can be difficult. There are numerous options but, lucky for you, there's a trick. Buy something you know you can maintain, instead of going by other people's recommendations. Then, from your choices, narrow down your vehicle by looking at the part's availability. If you break down in a Ford, for example, you won't find many spares or even a mechanic to work on your truck. You also want to look for the simplest option, preferably an engine without an ECU and an interior with the least electrics.
Now, you need to decide what kind of off-roading you'll be doing. Here's a scale from 1-5:
1- Light off-roading.
You'll mostly be sticking to the trail. Light bumps, steep inclines and a little sand and dirt will be a part of your journey. 4x4 not required.
2- Easy Off-Roading,
You'll be sticking to the main trail and exploring the area around it. Light bumps, steep inclines, a little sand and dirt, large bumps, water crossings, and mud will be part of your journey. 4x4 might be required.
3- Medium Off-roading.
No trails for you. Steep inclines, lots sand and dirt, large bumps, medium-large rocks, deep water crossings, and deep mud will be part of your journey. Permanent 4x4 will be required
4- Hard-core Off-roading.
Off-road or no road is your motto. Steep and slippery inclines, deep sand and dirt, large bumps, large rocks, deep water crossings, and deep mud will be part of your journey. 4x4 with locking diffs and low range required.
5- Extreme Off-roading.
You need something to tackle any terrain without asking questions. It shouldn't squeak or sputter during any of your journey. It tackles any terrain you can imagine.
Now, you should have a rough idea of what your going to be doing and what kind of terrain you will be tackling with your 4x4. There are several types of off-road machines. Here's a run-down off all the types and prices (for PKDM):
Mini or Kei 4x4's
Price: Mini, or Kei 4x4's are relativity cheap. They can range from PKR 300,000 used to around PKR 600,000 new.
Off-Road: Although cheap, they are relativity useless off-road. They can tackle the little things, like hills and sand but fail at mostly everything else.
On-Road: If you have a family, they're pretty practical for daily use. They get excellent fuel economy (14+ KM/L) and are small enough for city use. The fit four people, but the back seats can be very uncomfortable.
Engines: They usually come in 600cc to 1000cc petrol fittings with no diesel option. Finding a manual is also a challenge.
Off-Road Rating: 1-2
Examples: Mini Pajero, Pajero iO/Pajero Jr., Suzuki Carry 4x4, Terios Kid, Suzuki Samurai, Suzuki Jimny.
Compact SUV's

Price: Small SUV's can range from PKR 300,000 used to 20,00,000 new. Older and cheaper compact 4x4's can be found at military auctions in running and restorable condition.
Off-Road: The light chassis of smaller compact jeeps allow them to travel most places the Mini/Kei 4x4's are welcome. They can be as nimble as full size Land Cruisers and just as good off-road without any modifications.
On-Road: They are relativity cheap to maintain. The fuel mileage may be a bit lower (8-12 KM/L)than the Mini's, but not by much. All come with enough room to seat 4 adults comfortably.
Engine: Newer Compacts come with smaller, 2000cc to 3000cc engines. older jeeps have more flexibility in engines and gearboxes.
Off-Road Rating: 2-5
Examples: Jeep Wrangler, Jeep CJ, Suzuki Viatara, BMW X3, Nissan Xterra, Mitsubishi Outlander, Daihatsu Rocky, FJ Cruiser, Defender 90, Prado 3DR, Patrol 3DR, Pajero 3DR
Mid-Size SUV's

Price: Newer SUV's can cost upwards of PKR 20,00,000., and most, if not all, are imports.
Off-Road: The older, 90's models are almost flawless off road. Though, their body size and wheel base may be an inconvenience on rocky terrain. Newer import models are more eco-orientated and sacrifice power for miles per gallon.
On-Road: Their size may be an inconvenience in some places, but most are no longer than large sedans. Some are also available in short wheel-base models. Newer petrol models get around 7-10KM/L
Engines: Mid-Sizes share engines with their Compact companions rated at 2000cc to 4000cc
Off-Road Rating: 3-4
Examples: Toyota Surf, Land Rover Defender 110, Land Cruiser Prado
Full Size SUV's

Price: Be prepared to dish out huge money for full size SUV's. Even older ones can go for PKR 20,00,000 and newer ones up to PKR 90,00,000.
Off-Road: Full size SUV's like the Toyota Land Cruiser have a world-wide reputation of being the masters of all terrain.
On-Road: These cars are not very practical in city use. Their large, cumbersome size gets them stuck in most areas. Their fuel mileage is also poor compared to others at an average 7KM/L. Their large luggage capacity makes it a more than ideal tourer, fitting 7 passengers.
Engines: Engines vary from 4000cc up to 7000cc V12 German beasts
Off-Road Rating: 3-5
Examples: Toyota Land Cruiser, Nissan Patrol, Mitsubishi Pajero, Toyota Sequoia, Audi Q7, Mercedes G-Wagon
Pick-up Trucks

Price: Pick-ups go by a sizing chart similar to SUV's (Kei, Compact, Mid-size, Full-Size) and follow a similar pricing pattern.
Off-Road: Pick-ups sacrifice interior space for weight. They are light and swiftly go over any terrain. The most popular Pick-ups are Toyota Hilux and the imported Toyota Hilux Vigo.
On-Road: Pick-ups can be very practical if you're hauling around goods, or even towing. Their size can be an issue if you own a mid to full size truck.
Engines: Engines vary by size, see the SUV charts.
Off-Road Rating: 3-5
Examples: Toyota Hilux, Suzuki Carry 4x4, Nissan Frontier
Large Trucks

Price: Depends on vehicle
Off-Road: These trucks are as good as large SUV's off road and boast massive ground clearance. They are available in both 4X4 and 6X6 configurations and are large enough to haul an army. The downside? Forested areas and small paths. They are almost impossible to navigate though small mountainous areas.
On-Road: Stick to the highways...
Engines: Engines range from 9000cc to 12000cc diesel.
Off-Road Rating: 2-4
Examples: Bedford, Isuzu, Mercedes Unimog
Now you have a good idea of what you want. So what'll it be? Diesel or petrol?
Diesel and petrol engines both have their drawbacks. Petrol engines have a higher top speed than diesel rivals but lack the low-rpm torque that diesel engines have that help them up steep ridges and over obstacles. Diesel engines are extremely simple and easy to maintain, but don't have the reliability of the petrol engines. If you have a simple problem in a petrol, it'll be able to limp back to a mechanic. But on a diesel, it might not make it back.