First, for some details, this may seem redundant, but hang with me.
Organic brakes will have better stopping power for your manual brakes because they are softer and 'more sticky' than the metallic or carbon linings.
They also wear much faster... That's why modern brake systems use harder linings that last longer, but apply more pressure with a booster.
Organic brakes will also have the annoying trait of glazing and melting when they are heated up too much...
You will have to remove the pads, and sand the glazing off before the pads work correctly again.
(Takes an old fart to know these things!)
Metallic, or 'semi' metallic brake pads are usually used with low pressure power brake systems and on industrial applications.
Semi metallic pads (organic/metallic combo) are commonly used on passenger vehicles with 'Power' (power assist) systems.
These take heat a little better, last longer, but with the softer 'Organic' content they don't make noise or vibrate as much as true metallic linings.
True metallic linings are used in industrial applications.
They make nose, vibrate, don't overheat and liquify, and last a LONG time.
Carbon (Carbon/Carbon linings) are for racing and extreme heat applications, like aircraft.
The won't melt no matter how hot you get them, but the eat rotors very quickly and they are very expensive.
The first thing I'd do is make sure your master cylinder is putting out the pressure it's supposed to.
As master cylinders get old, the seals crack and wear, and the bore gets scratched/rusted.
All this contributes to a loss in pressure/braking power.
It's also possible that you have the wrong master cylinder... (wouldn't be the first time!)
If someone has upgraded your front calipers to the larger style from a 1/2 ton truck (they interchange) you don't have enough master cylinder.
If you rubber lines (doesn't have to be just the ones in the front) have given up, they may be swelling in robbing you of braking pressure.
If you master cylinder checks out, this may very well be the case...
Any air bubbles in the system cause problems.
Air compresses, and robs the hydraulic fluid of it's effectiveness, plus it rusts the brake components and lines...
Out of spec brake drums and rotors can cause a serious braking issue.
As the drum gets too big, shoes/pads get too worn or the rotor gets too thin (or the adjusters quit working) it takes more and more volume from the master cylinder to get the brakes to apply.
Clean, Inspect, Repair your rear brakes first. Make sure the adjusters are working, and the drums aren't oversized.
Taller tires give the wheel more mechanical advantage on the brakes.
It's like putting a longer handle on a wrench. Think of the tire to road contact patch as your hand, and the distance to the center of the wheel the handle of the wrench.
Taller tires give the rolling resistance (contact patch) a longer handle to leverage the brakes with...
If you have an undetected leak in the braking system, your safety valve has shut off either the front or back brakes, that would result in a SERIOUS braking issue!
Start by rolling at about 10 MPH in a parking lot, and jamming the brakes.
See which wheel(s) lock up and which don't...
This will give you a place to start from.
Does your jeep pull or shudder when you brake?
Pulling during driving (no brakes applied) is usually a sign of one or more brakes dragging.
Pulling during braking is usually a sign of a brake on one side not working.
Shudder (a back and forth wobble) is usually a warped rotor.
Warped rotors are caused by...
1. A dipstick that doesn't know how to use a torque wrench or torque limiter when installing wheel lug nuts.
2. Overheated rotors. The cheap Chinese rotors warp very easily since the Chinese haven't learned about metallurgy or heat treating...
3. A 'Sticking' brake caliper. When a caliper hangs up or the piston sticks the pads rub the rotor constantly, so the rotor never has a chance to cool down.
When you apply the brakes the next time, the rotor overheats and warps, and you have a problem...