If it is true 3:ed as they say, you donīt need 17 for charisma, you need 10+ level of spell to be able to cast the spells, however you gain a tremendous lot of having a high charisma as a Paladin, + to saving throws, smit ability is dependent on charisma modifier. The four most important ones are genrally dex dexterity gives better initiative, reflex saving throw, distance weapon to hit modifier. Constitution. Hitpoint, fortitude save, hitpoints hitpoints!
Wisdom, saving throw related and mostly for clerics, but against thoose mind spells, every fighter class better get a good wisdom or they are a walking timebomb!!
Strength. Melee fighting extraordinar ability, in this game granted as one of the most valid one for any fighte class. To hit, to carry, to damage. Very important for fighters since they are going to run around in a tincan suit smashing opponents..
Charisma for the Paladin is well, very good however since that score is used to smite and the grace-bonus saving throws.
Donīt go below 10 in any abilities if you can afford it! Under ten and there is a penalty! Also, read the manual before you o so you can plan your character ahead, to get an extra notch for when you receive your ability point, (1 point/4 levels).