Elites - here's where a lot of the meat of the CSM codex is, especially as so many of the units can be turned into Troops with the right HQ picks.
Chosen - lots of weapon options, can buy marks, icons, veterans of the long war (VotlW), Rhino. No Infiltrate, but two base attacks. Instead of doing things on their own (at least, how I used to use them - infiltrate/outflank into enemy area and summon/teleport in on their icon), nowadays I think they would be better used in support of other units as a fire brigade. 5-10 size.
Possessed - Good stats, Fleet, random benefits each turn in combat that all help deal more damage. 5-20 unit size. Can take marks, icons, veterans of the long war, Rhino. Seem better than before, but with so many other good CC type units in the book, may not see wide use.
Chaos Terminators - Slightly more expensive base, includes one champion, no longer able to upgrade more. Same types of weapons, costs fiddled with a bit. Marks, icons, VotlW, Land Raider. 3-10 size.
Helbrute - ie Chaos Dreadnought. Pretty basic, various weapon options, including thunder hammer or power scourge (lower WS of enemy models in btb), but no vehicle upgrades, so no extra armor or possession. Crazed only when takes damage, not nearly as bad. No more shooting friendlies.
Mutilators - CC oblits. Ugly. Can get marks and VotlW. 1-3 size. Can't take same weapon twice in a row. For these and oblits, I'd expect marks to be Nurgle (so T5 and can't be ID'd by S8-9) or Tzeentch for the 4+ inv.
Cult units - all size 5-20, all Fearless. Can take their god-specific icon, Rhino. Thousand Sons have VotlW built in, rest can buy it.
Khorne Berzerkers - one base attack, still WS5. Will still have old # of attacks on first turn of combat, but lower after that. Still have Furious Charge base. A little cheaper to start, can buy AP4 chainaxes.
Thousand Sons - still get AP3 inferno bolts, 4+ inv, slow and purposeful.
Plague Marines - As before, plus their CCW is a plague knife - 4+ poisoned, which is a definite boost.
Noise Marines - cheaper, even if you give CCW, sonic blasters cheaper and ignore cover (as do all sonic weapons), are salvo 2/3 so 2 shots at 12" if move, 3 shots at 24" if stationary, can't assault after firing either way. Can have two blastmasters if have full unit of 20. At first look seem like a pretty solid shooting unit, and overwatch with a ton of shots and doom sirens along with I5 should help them hold their own in an assault.
Chaos Bikers - 3-10, start out pretty cheap but with marks, icons, weapon upgrades, VotlW, can get expensive pretty quickly. My initial thoughts lean Khornate with the Banner of Wrath and be a stupidly fast missile, but there are certainly lots of ways to build them.
Chaos Spawn - 1-5 size, actually take up a slot now. Cheaper, better, controllable, able to take marks.
Raptors - 5-10 size. Cheaper, can buy marks, icons, VotlW.
Warp Talons - sort of possessed raptors, with special nova-type blinding attack when they deep strike in. 5-10 unit size. Have claws so sharp they can cut through dimensions, which apparently only takes AP3 since they have twin lightning claws. Can take marks, VotlW, but no icons. With VotlW and Mark of Slaanesh would make pretty disgusting MEQ killers.
Heldrake - that dragon thing. It's a flyer that can be tough, not terribly overwhelming, but doubtless can be useful. I just don't want to have to haul the thing around.
Havocs - 5-10 size. Pretty similar to before, can still do special weapons, can take flakk upgrade for their missile launchers. Why the extra k? For killy! Or something. The extra k makes it look more Orky to me, but what do I know? As you probably guessed, can take marks, icons, VotlW, Rhino.
Obliterator - same story, still ugly. Can take marks and VotlW, but can't take same weapon twice in a row.
Defiler - lots more expensive, extra rules make it more survivable so maybe it balances out? I love the crazy things, so I'll probably keep using them regardless. Remember those Dirge Casters? Slap one on these things to avoid Overwatch in case you're within 6" of the enemy when you declare a charge and skip that moment of dread when the other guy drops those melta dice looking for 6s.
Forgefiend and Maulerfiend - Forgefiend seems a little pricy but kicks out some good firepower. Maulerfiend is fast, but is begging to be tarpitted. It feels like a group of them would be awesome in some kind of Apocalypse scenario where they could rush across and tear open a section of fortress or kneecap a Titan, but not sure about regular games.
Land Raider, Predator, Vindicator, Storm Eagle - Just kidding on that last one. They're tanks, they have guns, you know what they can do. Dirge Caster on the Land Raider if you're transporting an assault unit. Dakkapred 95pts, Tri-las Annihilator 140pts.
That's pretty much it!