I am not a fan of talon or slayer. So, I am not going to comment on those. The other three listed are some of my favorite characters in the game (top 10 stuff).
None of my builds are min-max but they do the job just fine.
Justicar: I don't do the reave > shoot cycle. Acolyte > pull > reave/sphere for all the mooks. Pull + reave for enemies at range, pull + sphere for close by enemies.
Why even use pull + sphere? Because it produces some of the best ragdoll moments in the game. It's extremely hilarious.
For bosses, basically alternate reave and sphere, and make use of the sphere's warp effect to chain BEs.
Collector: Once again, I don't play the prime + shoot w/warp ammo way. Too boring for my liking. This guy is a powerhouse but it might take a while to get a hang of his cooldowns. The way I play is: launch DS, cast DC on one enemy and then spam swarms to get as many BEs as possible. Shoot a bit and finally demolish the stragglers with sphere detonation. For bosses, I make very little use of swarms as I want them primed for longer durations (for warp ammo). But I do occasionally use it for some CC.
A trick: Off-host, you can cancel the CD of SS with DC. Summon the swarms, and as soon as you see them appear around you, cast DC. You'll only have to deal with DC's cooldown and not the long SS cooldown.
Another note about SS and DS (very useful on-host when the above trick fails): When you run out of swarms, don't immediately summon them. Launch a sphere towards enemy(ies) and then summon swarms. As the swarms appear around you, detonate the sphere. This way, instead of incurring two separate long cooldowns, you'll virtually be dealing with just one. 
Phoenix Vanguard: Firstly,

Hands down, the best vanguard to use the bonus power evo. He is also the ONLY vanguard that can self-detonate 6+6 BE on all defenses.
BC boosted smash is very powerful. Stack as much power boosting mods/gear and his smash hits like a truck. IIRC, it is one of the highest spike damaging powers in the game.
I use warp ammo because I want to pull off as many BEs with him and a tech ammo will ruin it. So, fk that. But if you want to quickly detonate tech combos, disruptor or incendiary is good.
Cancelling smash with dodge roll/melee is very vital.