TLB is every PA user's favorite, at least when it comes to fighting other CMDRs. It simply causes the target to have lose lock every time they are hit by the effect. A very strong counter to subsystem targeting and seeker locks. Moderately useful against projectiles and anything gimbaled in general. Mostly useless against fixed hiscan, except at extreme range or when they are going for a specific sub-system. It's of limited utility vs. NPCs as they don't subsystem target and reacquire lock almost instantly.
Dispersal is handy vs. gimbals and turrets. It functions like a single target chaff that has a cool down and can significantly extend the utility of chaff; you chaff once the dispersal effect fades on the target and by the time the chaff expires, the cooldown on dispersal will be up and you'll likely have landed another dispersal shot.
Dazzle is of more limited utility. It reduces the resolve range of sensors to a very low level, but since you've just shot someone, you're at least partially resolved to them anyway, so it's net effect is minimal outside of wing fights/support roles (where preventing someone else from being targeted is a big help), except for reducing gimbal tracking arc.
TLB's effect is generally most pronounced, most universal, and lacks a cooldown, so this is what you should take first, and probably second (on separate triggers, ideally). If you have more than two PAs, you can take the other effects.