As promised I'm going to summarise the pros & cons of all the special characters then in a few subsequent posts I'll give some sample army lists to try and get people using more interesting armies!
A full list of the articles in this series is on the right of the blog and if you're considering using any of the special characters I suggest reading them. This list of pros and cons is just to give you a guide. Some characters look like they have far more of one than another but that doesn't necessarily mean you should use them (or not). Bear in mind you need to pick a character that suits your army style.
Pros: Powerful psyker, can use two powers per turn plus powerful Lord of Tempests. Possibly the best anti-psychic in the game (nullifies on 3+, 24" range). Durable 2+/4+ save.
Cons: Not great in combat, only two wounds and not eternal makes him vulnerable for the points. High points cost particularly with terminator armour. Minimal army benefits.
Best uses: Terminator bodyguard sat on an objective or with long fangs blasting away with lightning.
Pros: Eternal warrior, 3 wounds, 2+/4+ save and stubborn will keep him alive. Living legend can make an assault phase pretty lethal. High King makes a unit either great at combat or shooting. Can strike at I5 but option of power fist. Wolf Guard become troops, freeing up elite slots. Lethal in combat.
Cons: At higher points can limit army as WG must be troops. Extremely high points cost can put him out of contention in 2000pts or less. High King makes his use a tricky choice.
Best uses: Large, well equipped unit of terminators in a land raider or drop pod. Alternatively, gives long fangs relentless or tank hunters but wastes his CC prowess.
Pros: Cheaper option than Logan. Ablative wounds from fen wolves. Furious charge for a unit gives I5 for them and I6 for him. Once per game gives it to more units. Insane amount of attacks on the charge (possibly) if used in a large unit. Saga can give him even more attacks. High strength thanks for FC and frost blade. Invulnerable save.
Cons: Relies on getting the charge. Only gets a 3+ basic save and no eternal warrior makes him vulnerable to power fists and high strength shots. High cost for someone that can be killed so easily.
Best uses: Stick him in a rhino or drop pod with a full strength unit of grey hunters and pile him into a crucial enemy unit. Pop a standard and you're almost guaranteed to annihilate them (should you get the charge).
Bjorn the Fell-Handed
Pros: Venerable, AV13 and 5+ save makes him durable. Ability to dreadlock a unit. Bonus objective which can come in handy. High strength even in CC weapon destroyed. Gives you option to re-roll for deployment. Can soak up a lot of fire which gives a good distraction to protect the rest of your force.
Cons: Must die to make rest of army fearless. Additional objective can back-fire badly and loses D3 KP if not held in annihilation games. No drop pod means he'll have a long walk to get into combat and one lucky shot could potentially cost you 270pts. High cost over a standard dread without significant improvements.
Best uses: Counter charge on an objective/protect long fangs. Hug cover and try and dread-lock an opponent.
Ulrik the Slayer
Pros: Low points cost above a standard wolf priest makes him easier to include. Awesome against high toughness such as daemons/big tyranids. Army wide benefit from Wolf-Helm plus difficult for an IC to hit in combat. Makes his unit fearless. Plasma pistol can come in handy.
Cons: Vanilla wolf priest gives a lot of the same benefits but more flexibility with the preferred enemy. Only two wounds, no eternal warrior and T4 makes him vulnerable to power fists etc.
Best uses: Large unit of GH or BC. Almost a must against Tyranids/Daemons. Use Mentor to boost a dreadnought, lone wolf or PF model.
Pros: Big target to distract your opponent away from the rest of your army. S5 and ablative wounds make him durable. Fen wolves can be taken as troops and will have better stats thanks to Saga. High strength, rending, wolf claws and potential for a lot of attacks makes him deadly in combat. Potential to engage a unit 24" away in combat (12" charge range). Low points cost makes him easy to include.
Cons: No invulnerable save - railguns and S10 characters are not your friends. Needs a change in army style to be really effective.
Best uses: Give him a TWC bodyguard (with a storm shield) and get him in on a horde of orks/nids. Solo with fen wolves could be tricky but worth a go.
Pros: Good against ICs or MCs. Pretty cheap to include and can be split from WG squad to lead another unit. Throw the hammer to de-mech your target first. Storm shield without the downside. Eternal warrior and terminator armour make him sturdy. Large number of thunder hammer attacks will make him scary to your opponents.
Cons: Not an independent character so some benefits are wasted. No model available (but easy to convert). No unit or army-wide benefits (since he's just an upgrade character).
Best uses: Upgrade a terminator squad and go on the hunt for high toughness stuff. Drop pod him in near some juicy tanks or heavy weapons teams.
Lukas the Trickster
Pros: Last Laugh has the potential to make him more than pay for himself. Good number of attacks and re-roll from claw will make a mess of a lot of things in combat. Cheapest of all the characters listed here so not going to break the bank to include him.
Cons: Have to get him killed to make the most of him. Doesn't really benefit his unit. Pelt is pretty useless since he needs to be alone and at that point you probably want him to die. Must include Blood Claws to use him, relies on charge. Limits leadership of his unit.
Best uses: Upgrade a 15 man blood claw squad and give them a wolf priest. If you've got the points stick that little lot in an LR Crusader and ensure you get the charge. Find something juicy for him to trap in stasis forever and watch your opponent scrabble to find some reason why his valuable model isn't removed from the table!
I hope this series will have at least encouraged people to give the special characters a go. I know they're a lot of points but if you pick a couple and give them a go I'm sure you won't be disappointed. We showed at the tournament that sometimes an SC can be lethal when used right. Don't expect them to win games for you but sometimes the result of a crucial combat can be changed by their presence.
The alternative is to create your own characters with their own backstory and benefits. This can either be using the rules from an SC with a different name or by tooling up a wolf lord or battle leader. The codex gives you some great options for them and the Sagas give them a bit more flavour.
Let me know if you try any of them or have problems finding a role for them in your army. If nothing else they're (mostly) fantastic looking models to have on the table and people will respect you more for using them than boring stats lists. Remember 40K doesn't always have to be super competitive!