Which do you think is better and for what type of build?
On the Sensor targeting assalt does that mean if a ship has you targeted and is attacking you and the proc goes off that that they cant target you and thus cant fire on you until the proc wears off?

Honestly, the Emergency Secondary Shielding is nice no matter what you play as, just because...it's free shields if you get critted. Nothing bad about that at all IMO.

In PvE, the Sensor thing isn't too vital, because most NPCs are just huge, slow, stupid targets anyways, so placating them rarely helps when you could still just be killing them in other ways.

It's not that's it is bad to do so, just that it's not very vital to do so.

To me the shields are better option due to they adding to your survival in any space senario. While sensor targeting is only one or two seconds in duration and doesn't do you much good when you are in a 1 vs many environment. And in solo PvE, most targets are dead before you even proc.

so it looks like thats two people for shields any other opinions out there?

Well... sensor assault only procs when you crit...so if you arent using cannons and dont have a hiigh enough crit chance it probably wont do you much good.
where as, emergency shiels procs when your crit'ed so given that its a gaurentee some one will get you, you will probably get more mileage out of the shielding.

Shields IMO as already mentioned by others.

OnCritShieldHealProc (A) vs. OnCritPlacProc (B)

(A) 20% proc based on their ability to crit you to regen X amount of shields. 10s CD.

(B) 20% proc based on your ability to crit them to placate them for 2s. Various discussions on what the CD actually is, whether it's tied to the ability or the target, whether there's actually any immunity, whether there's a CD, etc, etc, etc.

Go into orbit around ESD, Qo'nos, etc, etc (basically, don't be on the ground or in sector space).

Look at the amount for that shield heal. You can get that a max every 10s if somebody or something crits you.

Compare that to the amount of damage you might take in 2s. Also consider the abilities an enemy may be using on you that the placate could break. Also consider how this works in tandem with KHG/AMACO shields. Look around for a post from a Dev confirming whether or not the passive can only affect a single target or not - if not, consider the potential of not taking damage for 2s from multiple targets because of FAW, CSV, TS, etc, etc, etc. If so, don't consider that - because it won't matter.

Then look back a that shield heal.

Make your choice.

Something to keep in mind - if you're trying to play a tank role, you're not going to want the enemy to target somebody else, eh? Then again, 2s can pass pretty fast and the target may not even pick up another target before going back to you...but that's a gamble, eh?