Agent of the Unbroken Circle (D387)
This is a +Leader PP. Insight is a good skill you're great at, so getting free training in that isn't worthless, like the training in Streetwise is. The combat focus of the PP is handing out saving throws or helping saving throws, but since the main trigger isn't predictable, it's less useful than it would seem. The powers do have enough Dakka, for a change, but the kickers are weak. If you have access to Dice of Auspicious Fortune , then the 16th level feature gets better because of the increase odds you'll be able to use it when you need it, but that still means you're holding a known crit until after the party got dominated in some weird attempt to save the day.
Ardent Champion (DP)
This is a +striker PP, and it's good. The first +striker feature is the crit special, which should add around 3% to your crit rate (Note the FAQ/errata: your double rolls still need to hit). The best part about this feature is that it stacks with any other way you have of increasing your critical range. It also works out surprisingly well with Sage of Ages , even though the stats don't fit. The second +striker feature is the level 16 feature: free MBA on a crit. That rocks, actually, and basically requires you to get an expanded crit range through some mechanism (the feat in Dragon 382 is probably your best bet). It also means you don't need a Rending Axe (assuming your DM treats Rending as a free action, thus making the free attack/turn limit apply), and can go look for Bloodiron instead. If you have any multiattacks or a good assortment of minor-action attacks, the u12d will make the encounter. The other powers don't suck, which leaves the PP looking pretty good in the final analysis.
Dervish of Dawn (DP)
This is intended for a Martyr, and I don't just mean "Censure of Retribution", I mean a Martyr. The u12d turns everyone into a hit-point pinata, should your leader get sick of healing you. The AP feature gives you bonus saves, for when you got hit by something nasty. But really, Dreadnought is probably better, even though it's a fighter PP with powers you can't quite use.
Dread Imperator (DP)
This is for the Unitarians, and the features reflect that. If you do all fight in a nice scrum, come Epic the level 16 feature will give you few attacks each combat, but it could also just end up being a "Win More" feature, if the ally who crits finishes off the target. The u12d power gives allies a small boost if you're highly accurate, but the boost is almost too small to track. The daily has an awfully short duration. All in all, this is a nice level 16 feature looking for a Paragon Path to go with it.
Favored Soul (DP)
This is a class "make your character look cool" paragon path, but it doesn't suck. Because this paragon path gives you honest flight as it's level 16 feature. Not "as a move action", not "until the end of your turn", but honest flight. This makes it pretty good for Chasers, just because it gives you a better way to follow, and monsters that can't attack you are more likely to move away. There are no references to a secondary stat, so should you go ahead and buy an 18 starting Wisdom (pre-racial), this PP may look better than some others. Now, if you take Distant Vengeance , and spend most fights hovering out of the fray and throwing daggers, you'll have an incredibly boring I win button, and you can expect to get mobbed by flying brutes in the next combat. But you will win a few combats first.
Hammer of Judgment (PHB2)
This is really a very focused +controller PP. In particular, it turns push effects into harder forms of control. However, if you're not into pushing people, it's not worth looking at. Note, Unitarians have a slightly higher number of pushing powers than other censures. Using the encounter power or daily power on an action point will just do a silly amount of pushing (Close Burst 3, push (3|5)+2*Int_mod) giving you a second option to Divine Rage. There really ought to be some dangerous terrain somewhere within 15-21 squares, and there's a Combo with Thunderwave Staff that makes for a big AoE. The u12e is good for the Martyrs (although it duplicates a couple of class utility powers... but you can never have too many).
Oathsworn (PHB2)
This is a leaderish +striker PP. The defining feature is probably the u12d, which gives your entire party your reroll mechanic for a turn. If you have some rangers in your party, it's going to be a spectacularly good turn. But the rest of it isn't anywhere near as good, and the utility power is only good for one round per day. Watch out for the "drop a target, spend a surge" feature. Strikers have a habit of running out of surges, so this really doesn't help you long term. Prefer damage mitigation/avoidance to having more abilities to spend surges.
Relentless Slayer (DP)
All in all, a rather bad PP with a great level 20 daily power. (A better quicksilver stance wasn't good enough, they had to add 3W on to the front of it?) If you can figure out a way to take a better PP, but poach that power, do so (Traveler's Harlequin(D382)). The 12 level utility power might work if you shift as part of your hit (Overwhelming Strike), but otherwise is non-functional.
Serene Initiate (DP)
This is a +striker PP that should mostly work, except that it's optimizing the idle loop. Damage on a Miss is like your dual roll: it has an unexpectedly large effect on DPR. Except you shouldn't miss much. So the biggest change is going to be that Power Attack now makes more sense (huh). Scimitar Dance may be tempting, but in general the oath will keep your hit rate up, so just grab a Fullblade/Executioner's Axe like everyone else. Warning: the d20 can be completely wasted, so make sure you've spent all encounter attack powers before you use it so that it's at least reliable.
Unveiled Visage (PHB2)
This is a +striker PP that focuses on mobility. The only problem is that Avengers already have a TON of mobility. This one gives some flight (but teleporting is better, because it's not enough flight, except for the daily power). The attack powers are ... questionable, because neither is a melee power, and so you don't get your oath rerolls. All in all, if you want flight take Favored Soul. If you want Radiant Goodness , take Morninglord . Don't take this.
Watcher of Vengeance (D377)
This PP is a little confused. On analysis, it seems to be focused on Ninjas. The e11 doesn't unstealth you... the first 11th level feature is a defender feature, but nothing else in the PP is. The d20 is a nice sized immediate interrupt, as a reliable daily. If you know what you want to do, I doubt this PP will help you do it.
Watchful Shepherd (DP)
This is a bit of a +leader PP (gives out some healing) and a bit of a +Defender PP (self healing, and a "don't attack my friends" encounter power. The u12d is a encounter long +1 to hit, which is quite nice, but that's about the only nice part here. The main thing of note is that the attack powers are all melee touch implement powers.
Weapon of Fortune (DP)
Too many ways to hurt yourself, not enough ways to stack the deck. Signs of Favor certainly ought to work out in your favor, but that's the only one that seems to be a decent risk.
Zealous Assassin (PHB2)
Ignore the nominal +striker feature. It's weak sauce . (+1d6, with two conditions. Wha?). No, the real +striker feature is the level 16 one... which says "use surprising charge for every charge" (although that does mean you have to use a spear. Which will be targeting Reflex. Not exactly horrible). Pixies, of course, avoid this because they have the f16 as a racial heroic-tier feat. If you are not a chaser, then it's not as good Good for some Ninjas, but not anywhere near as good as Thuranni Shadow Killer or Darkstrider . The class also offers a large number of ways to get combat advantage, which again helps the pure avenger less than others. But reasonably damaging powers are nice.
Exorcist of the Silver Flame (EPG)
You do have a lot of Radiant Powers to go with the 16th level feature, but that's about all this has going for it. This is for Laser Clerics, not you.
Fortune Blessed (D384,Avandra)
Rolling more means more 1s, more 20s, and more 18s and 19s. Only the daily is a ranged implement attack, and the utility is incredibly good, actually. I don't see any specific tricks, but it's a good solid PP.
Morninglord (FRPG,Amaunator)
The key here is a different trick for lightsaber wielders: the 16th level feature adds 10 static damage, basically. You also get to crit on an 18+ on action points, and a bit more. The utility power and the 11th level feature are good enough to turn something else into your dump stat, but I can't see you having a real charisma to really milk it. The attack powers will want a holy symbol, but the nice synergy of Pure Glow with the level 16 feature is an Effect line.
Soulforged (D385,Moradin)
Everything you wield is a lightsaber. Of course, Painful Oath already did that. Has a great AP feature (recharge Fury's Advance or Relentless Stride ?) Has a good defensive u12e. Has a great d20. The 16th level feature is nice (two rounds at +1d10 damage, no matter the size of your opponent). The Stun part won't ever happen (you have to crit during your Channel Divinity power) but it will be godly when it does.