I’ll start by caveating that it does depends on your play style. Everything I say after this is purely my opinion and dice rolling ability and I’m sure others will be able to contradict in their views. Sven and I tend to take quite different lists and both seem to work as well as each other. There are characters that work well with each other in terms of buffing but just be aware not to build your list relying on these ‘handshakes’.
Sven likes Alan & Donna (1 shot cannon that probably isn’t ideal for a campaign
) but Carl works well with both Rick and/or Lori and Glenn & Maggie (as long as you chose the right versions) go well together.
I’d say look at their nerve value. Anything with low nerve is going to be panicking pretty early on and is then only good for cannon/zombie fodder, and in campaign terms is likely to lose you points. That said, I know of people who have successfully run characters like Sophia as supply grabbers or Liam with a leather jacket as a human shield to their main characters.
Secondly, consider the number of wounds/health points. I get a little twitchy with only 4 HPs on character (perhaps I need to be more tactical!) and would generally look for more if I could, but at this level, you’re likely to be limited.
Consider their specialisation. I’d recommend within your 3 starting survivors you should look at a bruiser, a runner and a tactician although the later tend to be rather points heavy so they might be your next purchase when you get some points to spend. Why the spread? Runners don’t need to make movement rolls when going over obstacles (50/50 roll that can stop any movement dead). Tacticians don’t need to roll when attempting to reduce the threat leave and some even reduce the level by a die roll.
You summed up firearms well. The advantage of attracting zombies when stood behind an enemy cannot be under-estimated. Rolling head-shots also means ammo-reload/jam rolls, so you really ought to consider a weapon that is reliable or purchasing an ammo reload – don’t rely on picking one up when searching supplies – you’ll just get bandages and a booby-trap.
Without a firearm, how do you create mayhem and why should you want to? Well when the threat tracker reaches 18, the game ends at the end of that turn, so you may well wish to accelerate the tracker that way, especially if you are in the lead or you opponent hasn’t reached their win conditions. Again Sven quite likes using grenades on expendable characters…
Definitely give everyone a weapon of sorts. Firstly I’d go for more lower power dice over fewer better dice. I take 2 white and a red dice over a blue and white any day. Remember that it’s the difference in final scores that do the damage. Also pay attention to the special rules with weapons. Sharp, Bludgeon and Dual wield all confer bonuses that should work in harmony with your survivors. A small knife (3pts) is a really cheap way of getting the dual wield bonus working.
Personally I steer away from weapons that amputate – never used it and by the time a survivor needs it, they’re not going to survive the amputation. If it comes with dual wield and sharp, bonus, but I wouldn’t get a weapon just to get amputate.
You could go with 2 really well armed, high wound, high points characters (I’ve done it on occasion) but remember you are losing activations and actions, and if some of those actions are 50/50 rolls that’s quite a gamble. Also you’ve only got a couple of targets to spread incoming fire over rather than 3 or even 4.
Hope my ten pence helps…