Let's start with Space Marines! The vanilla kind! I have had quite a few battles with them, and can speak from experience about them.
Let's look at what units gain value against each other, and which ones lose value.
Bloodcrushers, Flamers, Chariots of Tzeentch, bloodletters to a degree, and screamers all become more effective against Space Marines.
Bloodcrushers can rampage through any combat unit Marines have to offer, and thus gain value: they need rending, though, in case they get assaulted by a dreadnought.
Bloodletters can rip through the more shooting-focused units, like tacticals, after they are disembarked: they need 10-man squads though, as you'll lose 50-75% from shooting before you close: but even 3 can kill a 5-man tactical squad in a couple rounds of CC, especially if they get the charge.
Screamers are largely vital as a suicide unit, because they WILL have a landraider, and you WILL need it dead. Of course, the screamers will also be dead, but...
Flamers can punish those disembarked terminators immensely, bypassing their valuable 2+ and going straight for the 5++: with about a 5-man squad and a little luck, a 5-7 terminator squad can be wiped out in one turn. The extra, mobile Bolt is also appreciated, but warpfire is largely useless, as even scouts will be getting their cover most of the time.
Chariots will be earning their keep, as they will be very, very busy killing rhinos and rhino-based chassis like predators, by getting into side and rear arcs.
As for Space Marines, Thundersheilds actually lose value- equal-point bloodcrushers will wipe them out before they can attack back. Land raiders stay about the same- while their usefulness as a transport is nearly worthless, as there is no gunline for them to dump thunderdeath into, their AV14 is immensely more useful against Daemons, who have only screamers and assaults to rely on.
Any close combat unit, actually, is largely outclassed, especially ones that rely on and pay for power weapons.
However, high RoF and high AP weapons gain value, as all invuls means you want to be forcing saves, not ignoring them. Heavy bolters, assault cannons, and even normal bolters are much more valuable against Daemons- they get one or two turns of shooting against Daemons, and need to kill the close combat elements quickly.
In the end, I would say it depends on how the Daemon's reserves go. If they get lots of stuff early, the marines won't be able to shoot it all before it closes in and murders their precious shooting. If not, the marines can gun down units as they trickle in from reserves.
That's the end of the first installment of Against the Warriors of Realspace. What army would you all like analyzed next?