Start with the basics, and work your way up.

Tires. If they aren't good, braking distances will be long.

Tire pressure. If it isn't right, especially if it unbalances the truck, braking distances will be long.

Hydraulics. If the fluid isn't good, there's air in it, or the components aren't in good shape, braking distances will be long.

Then, and only then, should you go looking into better pads and maybe rotors.

'97 T-100 SR5
'86 Toyota's, the variety pack (all gone)