I'm strongly against one-shot kills (with the possible exception of being shot at by a tank or an artillery piece). It kills any semblance of a strategy and makes chance too big of a factor. And it also makes the alpha strike the default tactic. Too long TTK, however, is also something to avoid - turns any conflict into indecisive slugfests. As in all things, a balance is required.
I am, surprisingly, for One-Shot-Kill weapons....where appropriate. The fact I could pop people with a 'lascannon' three times in SM yet not kill them pissed me the hell off, because the lag and shoody hit-boxing on that game made getting headshots a nigh impossible game of blind luck. Not to mention all the rolling marines all over the damn place... You get hit with a lascannon square on? Dead. Over very nearly dead. You eat a Leman Russ battlecannon to the face? Dead. Power fist/klaw/thunder hammer square on your head? Dead. Those weapons are, in lore, already balanced. The Lascannon should have a recharge time per shot, poossibly limited ammo, it's a single shot weapon anyway so is much harder to hit moving, small targets (it's an anti-tank weapon for christ sakes, which utter moron turned it into a godawful sniper wannabe?) Leman Russ cannon? It's on a tank, which is in itself an anti-armour magnet, has blind spots, can't move that fast, will likely be much less lethal with pure splash damage than direct hit damage. Fist/Klaw/Hammer? Melee weapon, slow swing, has to be within swiping distance. And if you're a pure ranged type that let them get that close, either they're just that good or it's your own damn fault. Here is to a game that might finally break the 'every race is the same with recolours' bullshit cycle...
bolter to the face? your face should fucking explode unless you have a really nice helmet. ...or plot armor...
I think for melee TTK tends to be up to the players involved, their tactics and relative skill. I can keep parrying, rolling and stepping backwards against someone to prolong my life if I want to, or go all out and either kill or kill quickly. As for ranged weapons? Well, I think they should be the way the devs are describing them, not as short as some shooters and not as long as borderlands 2. If you run out of cover and headlong into the enemy, even if you're clad in ceremite, there should be a good chance of getting mowed down. There's a reason assault marines have jump packs to get into combat, it's to avoid the whole 'bullets' thing. No matter how you look at it, weapons in the 40k universe are deadly and should be that way in game, one shots are a part of warfare when we're looking at taking multimeltas and lascannons into battle.
TTK in Planetside 2 is actually what I would go for. If you are getting constantly hit for 3-5 seconds you should go down.
