People always argue about which Primarch would win in a 1v1 but I want to know which legions would fare the best?
If it was a full legion versus full legion, no Primarchs involved, no holding back for some reason, both fighting for control of a single planet which legion would come out on top?
Luna Wolves
After 2 long years of fighting within their own ranks (insert legion name) crumbles from exhaustion in the ruined mess of a world and the last remaining marine pulls off of his helmet to revel a large hydra stamped across his face.
Alpha Legion, every fucking time.
They might not even have to fire a single round of ammo.
Especially easy when they don't have primarch support to try and cunningly avoid the trap, because every legionaire can lead.
Ultramarines.
>Alpha Legion, every fucking time.
alpha legion are kind of shit without the direct command of their primarch
emperor's children (quality) or ultramarines (quality+quantity) would be the legions to come out on top.
*Solos your legion*
Nothin personal...
>Can't even beat Mortarion's stinkers
>no Primarchs involved
This is actually a huge oversight, the primarchs are the heart of their legions, exemplary commanders strategically, and even a significant logistical component for a protracted campaign.
It's particularly important for some legions in terms of character and tactics - the Raven Guard pre-Corax are vastly different from post-Corax.
There's also the legion fleets as well, though you said 1 planet, which limits that.
Thinking about it, if it's just 1v1 and includes fleet assets (and Primarchs) I might give good odds to the Imperial Fists, odd as that initially sounds.
Horus once remarked to Dorn
>"if I ever laid assault to a bastion possessed by you... then the war would last for all eternity, the best in attack matched by the best in defence."
Now obviously, it's Horus, and even before his first ideas of rebellions he was a flatterer and a smooth-talker, but this is Dorn he's talking to - proud, to be sure, but not the sort to be swayed by honeyed words, and always high in the Emperor's esteem anyway.
So if the guy who becomes Warmaster and leads the most successful legion that favours assault thinks that you're matched with him if you each work with your specialties, you're probably pretty good.
Second, the Fists have the biggest fleet of any legion, and at the heart of the fleet is the Phalanx, which is a fortress in space and perhaps the most powerful imperial starship straight-up. The closest other legion fleets are Horus's and the Dark Angels.
As such I'd say the only real contenders for the Sons of Horus's top spot are the Fists
1000 chapter strength. Ultramarines was at the top of my head 250,000