I think long term you would enjoy the 4-door Tracker more than the 2-door BECAUSE of the extra room you would have. A 4-door Tracker isn't a "large" vehicle by any measure except when comparing it to a 2-door model or a Samurai.
I've had three 2-door models and I enjoyed them when I simply used them for a commuter while working, but if intend to do more with your truck and haul a lot of gear or more people, even a 4-door Tracker will be challenged at times for space.
To my knowledge, the ZR2 Tracker was never offered in a 4-door with the 2 liter engine. Basic 4-door Trackers were. The 4-door ZR2s came equipped with the 2.5 liter V6 engine. The 2-door ZR2 Trackers came with the 2 liter engine. Besides the plastic fender cladding and some light factory skid plates, they are no different than other Trackers. The plastic fender cladding is problematic to replace when you break one of them and they leave holes in the body when removed. Between the 2 liter engine and the 2.5 liter engine, assuming both were well maintained, I would prefer the 2 liter engine all day long over the 2.5 liter because:
1. the ease and expense of repair. The 2 liter engine's water pump is separate from the block while the water pump on the 2.5 sits behind the front engine cover in example. To change a water pump on a 2.5 liter engine requires stripping the engine down more. When you replace the water pump or the timing chain on a 2.5 liter, you should change both because the labor to repair either is just about the same. Less cylinders generally = less repair costs
2. the difference in horsepower is negligible, in my opinion. The 2.5 generates about 19 more HP than the 2 liter.
3. better fuel economy with the 2 liter engine. The better fuel economy is money in your pocket as long as you own it. Even when slightly modified with more gearing and larger tires, the 2 liter equipped Tracker will give you better MPG than the stock 2.5 liter Tracker. I swapped my stock 4.62 gears for a set of 4.88 gears to run 30" tires and I can still reliably get 24 MPG out on the highway, which is down about 2 MPG before modifying the Tracker, but still almost 4 MPG better than a stock Tracker with a 2.5 engine. Your mileage may differ depending on your driving style and tire selection.
4. the slightly longer wheel base of a 4 door will also provide you a better ride, while not significantly reducing your off road ability.
If you intend to just use your Tracker to run off road and in the woods, a 2 door is a good choice as well. It really just depends on what you intend to use it for primarily. They are all reliable little trucks when properly maintained and the fun factor just keeps on going.
