Well...I think we're all well aware that SS2 is finally, actually, really, legitimately coming out now. So, I'm interested in knowing, before tomorrow, what people think are the best character builds (this includes skill trees too).

Lets just say the game encourages you to join the navy rather than the marines or OSA (agency in this game)

Because for most players the game penalizes you if you do not chose navy.

Hacking to level 3 (level 4 only gives you access to what.. some extra chests?)
Maxed Standard Weapons and enough Maintenance and Upgrade to keep the Assault Rifle in top shape.
PSI selection includes unlocks of all levels, Telekinesis, Invisibility, Healing, some hacking boosts and mandatory object cloning for ammo.
Oh, yeah, and that sweet wrench overhead swing.

I liked playing as an OSA agent. Sure, Navy is easier, but I found the PSI based character more interesting to start with.

From experience, I'd pick Navy in the beginning and focus on Hacking and Standard Weapons, as well as low-level Maintain. Shotgun and Pistol should be your main weapons until Hydroponics/Operations. Along the way, you may want to invest in Energy Weapons, and replace Wrench with Laser Rapier as your staple melee weapon. Once you find the first Assault Rifle (in Hydroponics I think), which is IMO the most useful weapon in the game, skill up so you can use it. Modify and Research are nice to have, but these should be low on your priority. For Upgrades, go with whatever you think better helps you survive (though I recommend having Lethal Weapon as one of them in the early game part).

For Stats, just increase as and when you think you need it. I would prioritise, in descending order of importance, Endurance, Agility, Strength, Cyber-affinity.

Sounds like a solid plan. :D

Like with any game of this type, there should not be a clear "right" answer here, it all comes down to what you want to play.

The 3 starting classes are:
Marine
Navy
O.S.A

Marines are the most straight forward. You get a point in standard weapons, then you get to pick between raising any of the 3 physical attributes by 2 and then one more weapon skill (plus possibly some cyber-affinity, i.e. tech) and finally one utility skill.

Navy will also net you a point in standard weapons at the start, but you'll get more utility skills if you go this rout (well, there is the possibility of going stat+utility->standard weapons->physical attribute, which would give you a very similar result to being a marine).

Picking either one will give you a similar gameplay experience.

O.S.A is different though. Here you will get a lot of psi skills. This class is harder early on, but getting your psi to a reasonable level is prohibitively expensive for the other classes, so if you want to be a psi-focused character, go with O.S.A

The important thing to note is that this game does not reward generalists. While you don't want to over-focus either, don't spend your valuable points on too many different skills. If you intend to go psi, then focus on psi, if not, then you should not spend many points at all here (though a little can still be helpful later on in the game).

When it comes to psi skills, are they primarily defense or utilitiy based? Or are their offensive abilities that means you need less focus on weapons.

Made some changes to my post, sorry; have another look.

This is so amazing but the news is bittersweet with SS1 still in limbo. I guess this does give hope for that one though. I really wondered if this would ever see release.

Generally, good build in SS2 lead to pretty boring and uneventful game.

What if you just tried the game yourself to see what you enjoy most?
I certainly intend to do it.

This. It's a survival horror. Figuring stuff out is just about the most important thing about it.

Needing to have a preset build is an unfortunate holdover from Diablo II (and probably earlier RPGs). The first time I played I maxed out strength, agility, and hacking, but was pretty low on most other skills. It made for some fun ninja-ing, but probably wasn't even close to an optimal build!

No its not and its not scary (to me at least)