As for me Chaos Space Marines, who are 10 000 years participating in eternal war, must have much more options. Few ideas I have:
Veterans are those who are killing for their Gods for 10.000 years already. There should be list of veteran skills and possibility to choose few of them. Also they have access to artificer weapons and armor (similar to loyal marines) and Terminator armor. All of them can have special weapons, because in 10.000 years they formed specialized groups. 2 Attacks in profile, because they are much more skilled than simple Marines. Also, in current Codex Chosen are able to buy power weapons, but it will cost 33 points for model, while you can buy Terminator for 30. So to make this option viable - power weapon cost should be lower (there is no point in rising Terminator cost, because it's already low in Loyal Codex, and rising it for Chaos will make Terminators not viable option).
Possessed Marines. In armies who are worshiping more than 2 Gods mutations are more common. If your army includes worshipers of more than 2 Gods (including Marks and Icons of Gods or cult troops) you must spread mutations on your squads. I am not sure what is the best way to do it, not all mutations are good one and of course depending on squad size there are different possibilities to have mutants.
Beggar Marines once proud and noble they lost everything they had. Being still powerful Space Marines and very useful on the battlefield they lost all their supply factories and artificers. Their armor breached and broken in many places, they have few bolter rounds and lost all other weapons. Now they are fighting for trophies and ammunition, serving to anyone who will offer them more than others.
- Cost about 10 points
- Ld value is 7, 8 for Champion.
- 4+ power armor. Some parts of armor are lost, some are no longer functional, and some are just taken by someone stronger.
- Wargear. Chainsword and Bolt Pistol. They are saving bolter rounds as treasure, not wasting more than one shot for single enemy.
- Must have Champion. Without strong leader they will fight each other or just will separate in groups too small to operate as combat unit. If Champion is killed - another one must be chosen on his place. Roll a dice, on result 5+ another Champion is selected, on 1-4 two of Marines will fight each other and one of them will die, remove him as casualty.
- Marauders. Beggar squads cannot have any special weapons until they'll salvage it from enemies. If Beggar Marines won the round they can try to take enemy weapons if they are fighting another Marines or Human race. They can take any ranged weapon or simple power weapons (but not Terminator's power weapon, because it's using more powerful energy sources). Roll a dice for each ranged weapon that looks useful to you (including bolters, meltaguns, plasmaguns, flamers, and heavy weapons), and on 4+ Beggar Marines can take it. Also there are some more valuable weapons, if you rolled 1 for Special Weapon or Heavy Weapon - marines are fighting for it and one of them receives wound and must immediately take armor save. You must write the list of weapons so your opponent will see it.
- Marks. Beggar Marines can use only Mark of Chaos Undivided for 10 points and Mark of Khorne for 30 points, because of nature of other Gods their worshipers will not make good Beggar Marines.
That's all for now. Later I will tell more ideas I have and some experience of using those units I suggested here.