It's great to see people pick up this hobby as someone that used to off road every other weekend in the spring and summer months.
My "truck" and off road experience is purely with Nissan's so I can speak to them.
TopsyCrett touched on several points and I agree with almost all of it.
In terms of affordability, I'd go with a Nissan hands down. The 4Runner's, older Taco's just simply (in my opinion) aren't worth what people are asking for them. You can get a Path/Xterra (I'd go with Xterra), do the necessary mods, repairs, and maintenance for sometimes less than the cost of a good condition, roughly rust free 4runner/Taco. Xterra prices however seem to be on the rise.
In terms of reliability, the older 3.3 (VG33) engines are quite bulletproof. They have timing belts just like the older Toyota engines so there's that to consider. They don't have common problems but distributors can go on those just like any older engine with a distributor. Maintenance is easy however #6 spark plug is quite the b*tch to replace.
All these engines leak from the rear main seal. Almost every one that comes through the shop does however only ~5% of them even drip enough to warrant replacing. Both my Path/Xterra had a rear main seal leak but never dripped and oil level was never a concern.
The 3.5 (VQ) is a solid engine. Much more power than the 3.3 it replaces however was slightly less reliable. Common issues such as leaks, ignition coils, occasional oil burners.
These Pathfinders/QX4's are not body on frame so they do have MacPherson strut front suspension but overall they are still quite capable off road. There are a variety of ways to lift them, ranging from body lifts (SF Creation), to Old Man Emu springs, to LR Defender rear springs (not range rover), front subframe drop 6 inch lifts. Depends on how severe you want to go.
The R50 generation can safely fit 31's (albeit on aftermarket wheels for backspacing, like Crager Soft 8's) with very minimal rubbing. On mine, I only had rubbing while revering fully cranked. If you are going to be lifting these, I recommend looking at WARN front hubs to replace the factory hubs. If you have the 00-04 Pathfinders with the electronic 4x4 system (dial), this won't be possible.
The Xterra's have no problem accommodating 31's and can go up to 33's stock. They are also body on frame. I absolutely loved mine and was very sad to see it go. If you can get one of these supercharged in good condition, they are quite the unicorn.
*For those wondering about the "pink milkshake of death", or more professionally called cross contamination, this only affected Path/X/Frontier 4.0L Automatic from 2005-2010. What do you do if you have one of these? Or are looking to buy one? Easy. If there are no signs of it having this problem (after test driving and checking fluid condition), replace the radiator with a new one (Nissan corrected the design 2011+), or bypass the radiator with a cooler.
I used to own a 98 Pathfinder years ago. It started off as just a beater to and fro work and as an extra car for my parents in the winter when it snowed.
It quickly turned into a project as I started modding it and experimenting at Triangle Beach. After several modifications I decided to start tackling some trails and FSR's.
Eventually it led me to dozens of off road journeys, mountains to climb, camp sites to reach, etc. My favorite trip is the Sts.Ailles FSR which takes you from Harrison Mills to Pemberton through the mountians - doable in 1 full day but really should be spread out over 2-3 to really enjoy.
It had a 1 inch body lift + OME heavy duty front/rear springs (2 inch lift), 31 inch Duratracs on Crager Soft 8, Bilstein 5125 on the rear, WARN front hubs.
It was then time for that to go and I moved onto a deal I simply couldn't pass on.
I got this Xterra for $500 with 320KM, full service history exclusively done at the dealer, always with OEM parts.
Did a bunch of repairs (heater core, valve cover gasket, replaced the sagging headliner, gave it a detail, and threw on GY Duratracs.
Unfortunately, I never got to off road it as it was written off 2 months after insuring it and 6 months into ownership due to a very frazzled motorist on an icy morning.
After that, I got my "attainable" dream truck - a unicorn. V8 Pathfinder.
I haven't done any off roading in this yet. I'll probably end up doing a few FSR's and camp with it but I've gotten out of off roading recently. Became too expensive of a hobby when you've got another car you want to do some mods to.
While it's nice to see more people get into off-roading, I have to repeats what's been said already.
1) Tell your friends and family where you are going in case something happens, especially if you are going alone (run out of gas, breakdown, no reception)
2) Avoid going alone
3) If you are on rough terrain, do NOT put your thumbs inside the steering wheel. ALWAYS on the outside unless you want broken fingers.
Happy off roading all!