Ok, so I think I've figured out the most power-gamy way to play this. I'd like to hear if you know a better way.
So, in the last game, the problem with VATs was that it missed shots that you the player could easily make. Also, you could get critical hits both in and out of VATs. Now, it's not the case.
Now, you can pull out a low action point weapon - the 10mm pistol seems like a good one - and make a bunch of shots of enemy torsos for 95% chance to hit. Then, once you accumulate enough points for a critical - the critical banker perk lets you save up several - you can choose an enemy that is all the way at the edge of a VATs range, with a 1% chance to hit their head, select their head, and mash spacebar.
You get a guaranteed hit! And it's whatever the headshot bonus is + critical hit damage! This is massive - it can instakill bullet sponge enemies. The 4 leaf clover perk means that regular body shots each have a chance of just filling your critical bar instantly, and it apparently maxes at a 45% chance, so a low AP body shot on a nearby enemy gives you a critical hit.
It looks like the optimal weapon might be pistols because of their lower AP cost. But you don't have to commit to any particular weapon, you can get a critical hit guaranteed headshot with the missile launcher as well.
So for combat, I think luck 9 (maybe luck 8 at character creation + bobblehead) and the associated perk tree gives you the most powerful character. VATs isn't just better offense, it's also defense because it slows down time and you take less damage from enemies in VATs and they get less time to shoot back.