Kabalites are the mainstay of my army and probably for the majority of other players. I prefer to run them at the bare minimum: 5 man squads, just a rifle on the Sybarite and one special weapon and also in Venom although I think I'm going to switch to Raiders (a point for another time I think).
Minimum squads and Special Weapons
As most people will have guessed, Dark eldar are all about their speed and mobility. They want to outpace and (generally) outshoot their opponent. The best way (IMO) to do this is to run minimum, bare bones units in transports. 5 man kabalite squads with no upgrades are 30 points, dirt cheap but don't really provide much beyond some poison shots. Generally I wouldn't run them like this, as unless you're using them to sit on an objective they will struggle to make their points back. From there, there is two ways of running them: Anti-infantry or anti-tank.
The Shredder is the special weapon of choice if you want some anti-infantry, at strength 5 and -1ap it really can do some work against low to medium toughness with low armour saves. The downside is that it's only 12" range and D6 shots, less than ideal but can definitely come in clutch against hordes. The range being that low means that you have to get close which Kabalites definitely don't want to do. in a pinch, this could also be pretty great against power armour as the strength 5 is higher than most space marines's toughness.
The Blaster is the other option if you want anti-tank. At 17 points, 1 shot and D6 it can be quite expensive for what it does but it does have some upsides. With 18" range it makes it easy enough to stay out of harms way and with -4AP it also ignores most Imperial vehicles armour save and most don't have Invuln saves. At 17 points it puts a 5 man squad to 47 points which IMO is a steal for the damage potential.
6+ man squads and Heavy weapons
The problem with bigger squads is that the bigger weapons unlocked at 10+ are too underwhelming for their points.
Dark lances are too swingy in my opinion. You have one shot which if you're in a vehicle you can't re-roll, which while high strength and AP is too random at D6 damage. When looking at the current state of 8th and Math-hammer, D6 dmg weaponry is not consistent enough. Generally lower strength, lower AP but high rate of fire and lower damage has a higher chance of doing damage. It's also 15 points which is too high IMO
10 points for a splinter cannon is not great especially when up against anything primaris or Mech-wall which is the majority of the meta currently. It suffers from the same thing that all poison weapons do curretly: no AP. If you're not running Flayed Skull, this point is made even worse, especially when up against any sort of power armour. However these can be really good picks when against something like Nids with hordes or big monsters and Orks. High rate of fire vs low armour saves is great.
When looking at these two options you also have to take into account the fact that you also have to pay for 5 more Kabalites than the minimum, while at only 30 points this can add up on top of the Heavy weapon and the base special weapon. As pointed out before I think that a splinter cannon can work really well vs orks and nids where you have so many low save models to shoot at.
As I pointed out above, Dark eldar and Kabalites especially want to be outpacing and moving out of harms way of targets. The best way to do this is with Transports, which in my opinion and my experience is really the only way you want to run Kabalites as they are far too squishy outside of them. With this in mide there are only two Transports in the codex, there Forgeworld options but I don't have any experience with these.
The venom is a maximum 5 man transport that comes with a splinter cannon on top and a twin splinter rifle underneath for a base of 65 points. It's fast, it's small and hard to hit. It has a 5+ Invuln save (all Dark eldar vehicles do) and an inbuilt -1 to hit, while only 6 wounds it can move 16" and is open topped meaning the passengers can shoot out of it. It can also replace the twin splinter rifles for another splinter cannon for 10pts, bumping this up to 75 points. There are two other vehcile equipment options options but in my opinion are not at all worth it as they require the venom to be in combat. Obviously this requires your kabalite squad to be a minimum size unit and until the re-do of the space marine codex (with it's ridiculous amount of re-rolls basically making the -1 to hit moot) Venoms were the obvious choice.
The Raider is a 10 man maximum transport that comes with a disintergrator cannon as standard. Where it lacks the -1 to hit that the venom has it makes up for in wounds, damage output and transport capacity. At 80 points with the base gun I think this really has a chance of knocking out the venom as top dog. With a ten man transport capacity it can either be used to transport a full 10 man squad or two 5 mans or even a 5 man and a court of the archon etc. You can switch the disintergrator for a dark lance but as I said above, generally the disintegrator does better statistically. The Raider is great if you really want to clear hordes, you could take a 10 man unit with a Shredder and a splinter cannon and give the Raider the Splinter racks vehicle upgrade (the only worth while upgrade and it's very situational IMO). This means at 12" range the gun boat will be putting out 3 Disintegrator shots, D6 blaster shots and 22 poison shots which explode on 6s to hit. With the Flayed Skull obsession they can re-roll 1s on poison weapons and ignore cover.
Sorry fo the massvie wall of text, it's a slow day at work. If you have any questions feel free to ask away!