DraQ, okay, here's what I'm thinking. 10 AP all round. Movement is first hex costs AG/2, rest is 1 AP. Attack AP costs don't change except through traits (where I can attach hefty penalties). Aimed and regular attacks cost the same AP (regular attacks are the exact same as aimed attacks only defaulted to the torso for convenience).
For ranged, you can spend additional AP's to aim. For melee you can spend additional AP's to add force to your attack and do more damage. The effects of both of these bottom out eventually (a horrible shot can't suddenly become a master marksman just by spending a lot of time aiming; every consecutive point spent will give less of a bonus than the last and the same goes for additional damage in melee).
For weapon base costs, I'm thinking 3 for knives/pistols/punches, 4 for spears/smg's/clubs/kicks, 5 for rifles/sledges and 6 for big guns. Shooting additional rounds will probably cost more AP on a decreasing scale to account for the fact that the use of firing more rounds decreases quite quickly even with high strength (I'm thinking 2-5 rounds = +1 AP, 6-20 rounds = +2 AP 21-max rounds = +3 AP).
Agility will thus only affect movement and defence (I'll have it have an effect on blocking and counter-attacking as well); in addition to a lot of skills. I'll also have to nerf INT a bit by reducing its effect on skill points, or just reduce skill points in general and increase the effect of atts on skills even further.
edit: just summarizing for myself what would be the systemic uses of each stat:
STR: Melee damage, carry weight, weapon handling, preventing knockdowns/disarms.
PER: ranged distance mods, sequence.
END: Hitpoints, Poison/Rad resistance, preventing knockouts/missed turns/crippling hits.
CHA: Number of party members.
INT: Number of skill points.
AGI: Move costs, defense against melee (based on unused AP), defense against ranged (based on hexes moved).
LUC: Crit chance.
Seems more or less balanced on the face of it... though I still think movement needs more of a boost; like I was saying, AP costs might be subtracted from the movecost... anyway, not sure yet.
edit 2: problem with agility right now is that it's the only one that doesn't have consistent "base" benefit. It's a benefit if you move or save up unspent AP's, but if you don't, it's useless. Even PER has sequence going for it if you choose against ranged weapons... just dislike the idea of a base dodge bonus (gets me into dodging bullets mode).
edit 3: maybe I'll just restore AGI's skill point governing supremacy, that way it's a solid choice for getting good base skill counts.