At this point we've fast attack and heavy spport left to go over. No need for ado...
Pros: Speed/mobility comes from being on the bike. They're decent at shooting up infantry with twin-linked bolters, and have the pistol/CCW of normal marines, so they've got a decent number of attacks in assault. Or, they can pick up a powerfist and some meltaguns and go vehicle-hunting.
Cons: Cost is the big kicker here. Bikers are 33 a head; a basic unit of 3 bikers costs you 99. Getting up to a reasonably 6ish bikes with a couple of meltaguns and a powerfist costs you in the neighborhood of 260 points. Icons only add to the expense, and while you might be tempted to go Nurgle Bikers for T6, you're still not uber-tough.
All in all, I want to like bikers, but in the end they're a bit expensive for the versatility. I suppose if you wanted to do a themed Chaos Biker list you could do decently; large squads + fists/meltas + icon of Chaos Glory or Khorne, but you are looking at about 1,000 points for your fast attack there. However, you're still not dedicated CC troops, and nastier choices like Harlequins, Nob Bikers, Termiantors and the like can still roll you.
Pros: Speed, and you get a focused unit. 2 attacks base, and you can pick up flamers or meltaguns, and the champ can access Lightning Claws. This lets you take a focused squad for anti-infantry (2 flamers, lightning claws) or a squad that can hunt bigger game or smaller game (powerfist, 2 meltaguns).
Cons: They're only DECENT in assault; again a hardcore melee unit can roll you. Seer Councils, Harlequins, genestealers, and the like are still BETTER than you. Raptors (especially Khornate ones. Are there any other kinds? No.) can crank out a solid volume of attacks (4 per model w/ Khorne and the charge), and have the speed to get the charge.
Overall? They're not BAD, but still aren't melee specialists. Still, they can roll up decent numbers of infantry if allowed to and are solid delivery systems for the powerfist, lightning claws, flamers and meltaguns.
....laughable. No armor save, slow and purposeful? At least they're beasts, so they CAN kind of truck it. Their movement looks pretty wonky, with a 'best of 2d6' + d6 fleet + 'best of 2d6 *2 charge'. I want to like them for the truly awesome plastic model, but these are really conversion fodder.
On Chaos Fast Attack
At the end of the day, chaos fast attack is really only suited for getting your troops into range a bit faster. Ask yourself if you can't do this with another squad of marines in a Rhino. I mean, 8 Khornate Raptors with a powerfist and meltaguns runs you 250; a ten-man Chaos Marine squad with same upgrades and a Rhino costs you 275. The Rhino requires anti-tank weapons to be dealt with, and can block LOS. Raptors...die to torrents of fire and can't block LOS.
Pros: 4 heavy OR special weapons.
Cons: They're basically Chosen that trade infiltrate and melee options for heavy weapon options.
Overall, they're a very versatile unit. If you're not using them as meltagun delivery systems, then I'm beginning to get a fondness for autocannon/missile launcher mixes as it's a versatile loadout that only wants for effectiveness against AV14.
Pros: If you need it dead, the Oblits probably have the weapon for it. Long-ranged tank busting, long-range anti-infantry, or a variety of twin-linked close-ranged weapons all on one platform. In a pinch, they're essentially terminators in assault. They can also Deep Strike, but you might not be using that option so much. Slow and Purposeful means they can advance and shoot as well.
Cons: Vulnerable to instant death. Honestly, that's about it for cons.
Overall? They really ARE a bit of a no-brainer choice. They're versatile in terms of heavy weapons and they can deep strike. The only thing they really worry about is S8, AP2 weapons, and then you just have to get cover.
Pros: They can get a decent amount of anti-infantry dakka for 115pts (autocannon, heavy bolter sponsons, havoc launcher). Alternatively, you can try to turn them into a tank-hunting platform for 130pts (autocannon, lascannon sponsons).
Cons: It's outshown by other heavy support choices because Oblits and Defilers can do more. Still, it's worth a look.
Overall, skip the extra options aside from a Havoc Launcher, and think about it in the dakka-pred configuration. Really, it's best for killing infantry and name me a Chaos unit that can't do that in some form or fashion.
Pros: BIG FREAKING GUN. If you go with Daemonic Posession, the enemy has to destroy the thing or get a 'weapon destroyed' result to stop you. It MUST be dealt with, and it can handle vehicles pretty well.
Cons: infantry get cover saves. It's such a priority target that you should be glad if it gets 1-2 shots off all game.
Overall? Use a single Vindy to draw fire, or bring three and have some fun. There's no other way to use it.
Pros: Versatile. You get a battle cannon, and in a pinch you can fleet and assault. Failing that, you've got a backup heavy flamer and twin-linked autocannon, but you shouldn't need those so much. Additionally, it ignores shaken/stunned results, so the enemy has to either immobilize it or pop the battlecannon off.
Cons: Defilers are too big to ever really get a cover save reliably. AV12 isn't super-sturdy. The kit costs? WS3, I3 won't save you from a monstrous creature beatdown, and even Dreadnoughts give you a run for your money at WS4/I4 in melee.
Overall, Defilers are versatile choices. They're good as-is, or possible with some of the guns traded for extra dreadnought close combat weapons. Expect them to draw lots of fire right from the get-go, though.
Chaos Land Raider
Pros: AV14. Long-ranged anti-tank. Can also transport and fire off assault troops in relative safety.
Cons: The Chaos Land Raider suffers from split personality. It WANTS to sit back and pop lascannon shots off, but it ALSO wants to rush forward at 12" a turn and throw marines into the fray. If you are using it to deliver assault troops, you will feel a faint sense of waste because you just CAN'T get full usage out of the Land Raider every turn.
Overall? I'm not a big fan of the Chaos Land Raider for this waste. It can get you termiantors into assault, but another use might be to take Chaos Terminators, take a Land Raider as a designated heavy support choice, and cram a minimal squad of marines into the Raider and sit it at home.
Chaos Heavy Support as a Whole
Chaos has a pretty tidy little heavy support section. Oblits win on sheer versatility, and for their ability to always have the right weapon at the right time. Havocs can sit back and shoot, or be used to get massed special weapons. The Defiler's another versatile choice. Vindys are fire magnets, Land Raiders are rolling contradictions, and Predators just kind of get outshone everywhere.
Pros: For 100 points, that's a pretty nasty statline. If he comes in at the right time, it's straight into assault, and he comes in accurately. WS8, S6, T6, and a 4+ invulnerable are all pretty nasty, especially with 4 attacks base. Four wounds is just icing on the cake.
Cons: You're reliant on reserve rolls to make him come in at the right time. Including one means spending points on several champions without taking melee upgrades. If the enemy has a way to single out and kill champs (IE: Telion, Mind War, etc.) then they can deny you the chance to summon the daemon. If he comes in at the wrong time, he's not particularly resilient to shooting.
Overall: A bit random. He's nasty IF he works right. If not? He kind of gets shot to death, but there's nothing like watching them roar right into assault from the get-go.
Pros: Decent number of attacks. Scoring unit.
Cons: Reliant on reserve rolls to come in and get directly into assault. T4, 5+ save is NOT exactly durable. They're only so-so in melee.
Overall: They can at least score, which is something. They open up tactical options in terms of dropping scoring units in places, BUT you have to have an icon nearby.
Summoned Daemons Overall
Random. Randomness is not the way to win. This isn't to say that Summoned Daemons are without use, but that you can't rely on them to always do what you want them to do. They're not bad, but they're not a top-tier choice. If you take randomness like this, you're saying "Alright, guy across the table...let's see what happens!" and be prepared to either laugh or cry.