"#000000">Strength - Strength is decent for assassins. Mostly used for meeting the pre-req for hide proficiency, heavy blade opportunity, and possibly light blade mastery. Suggested starting value 10-13, after racial bonuses.
Constitution - Con is a secondary for bleak disciples, and is good for nightstalkers to have some more HP. As with Str, it is one of the pre-reqs for hide proficiency, and is the only pre-req for hide armor spec. Suggested starting value 12-16, after raical bonuses. Bleak disciples are going to want to be on the upper end.
"#00BFFF">Dexterity - This is your main stat. Boosts attack rolls, damage rolls, Ref, AC, and initiative. Oh, did I mention this is your main stat? Live it, learn it, love it. Suggested starting value 16-18, after racial bonuses.
Intelligence - Yeah...it might be good for the "intelligent assassin" archetype...but no good class skills kick off of it, and no class feature uses it. Might be interesting if you want to MC wizard, swordmage, or artificer. Pretty much your dump stat. Suggested starting value of 8-10, after racial bonuses.
"#000000">Wisdom - Perception and insight are always good, but you're more likely boosting your Will defense with Cha. Really only useful if you're going to multiclass avenger. Suggested starting value of 10-14, after racial bonuses.
Charisma - Many class skills are Cha skills, and night stalkers get to add their Cha bonus to most damage rolls. Suggested starting value of 12-16, after racial bonuses. Night stalkers are going to want to be on the upper end.