Useful skills and less useful ones

[LokkNar]

After playing twice through the game back to back I came to the conclusion that scanning and psychology are basically useless. What is even the point of psychology? It's solely for flavor, and even in the beginning when you need it most, you can just invest in deduction instead and get the same results. Scanning gives you the ricochets, but they are very situational in my experience and thus not worth speccing into.

What is in my opinion the most useful skill to increase early on is deduction though. The increased XP gain from notes is massive and the 30% xp gain at lvl 10 means one extra skill point for every (excellent) evaluation. You can reach lvl 10 Deduction as early as the slaughterhouse.
On my last playthrough I maxed out every skill except psychology, which means I gained 71 skill points over the course of the game.

Combined with the secret 6.0 PCB you can find at the weapons expo, even the final boss took only five minutes altogether.

Is this how being Robert Cop feels like?

So tl;dr: In my humble opinion the skills, ordered from most useful to least useful are:

Deduction > Combat/Armor/Vitality > Engineering > [power gap] > Focus > Scanning >>>> Psychology