Slaanesh
CSM. Noise Marines are, in my opinion, the most underrated units in that codex. Even while moving, they get a ton of shots. Yeah, not a lot of AP3 stuff for marines, but with 20 bolter shots after the move, or 30 stationary, marines WILL die.
They also have the doom siren (Heavy Flamer with AP3, and assault) as well as I5. Against marines you can just soften 'em up and just assault and finish them off.
The only reason why I would NOT recommend this army to start is that it's expensive, and the hybrid metal-plastic kits for Noise Marines are a pain in the ass. (Not to mention ONE kit has ONE sonic blaster, nullifying the purpose of taking them, and that you have to shell out even more money to get one legit Noise Marines squad.)
.... Now that I think of it,
CSM might be a good way to go for you. (Yeah I'm kinda biased

)