I used to be into min maxing but my current opinion is that you're better off slightly accentuating those attributes which you want to play around, but not hurt yourself severly in any departament. You then count on further customizing your ability scores during gameplay.
My reasoning for this is that in PoE there are many opportunities to raise attribute scores on permanent or de facto permanent basis - rest bonuses, buffs, items, etc. So my advice is don't think of PoE's attribute scores as you used to think about D&D's attribute scores in the IE games. (Apparently this is one of the "flaws" Sawyer saw in D&D and the IE games and went on to "fix")
Second, I think the usefulness of having attribute scores above a certain threshold diminishes quickly - for example for every point in Dexterity you get a +2% increase in action speed, but this is 2% of your base action speed, and not cumulative to the action speed you end up with after the last time you increased the attribute. Hence, the 10th point you invest in Dexterity has a much smaller effect than the previous, and so on.
The same applies to the other attributes that give a percentage-based increase of a stat. The attributes that give you a flat bonus, like Perception gives to Accuracy seem more worthwile investing more points in, but again, I wouldn't go crazy. The same attribute point that could give me 35 instead of 34 accuracy might take away a valuable amount of my hit points or damage from my hits.
