Fluff wise,>best fleet
Black Templars because the entire chapter's in the damn Eternal Crusader fleet and they have the most numbers. Dark Angels would work, too, but only after taking into consideration their sorta consolidation of their successor chapters unlike Templars which are one huge Chapter>best guns
This can go many ways, but probably between Salamanders and Blood Ravens depending on whether you're looking at the crafted stuff or found relics respectively. I would say Blood Ravens cuz Chapter Master gear, Primarch gear, Adeptus Custodes gear, fucking anti Titan guns, etc. crazy shit.>most vehicles
Black Templars again. While they may not proportionally field as many vehicles as someone like White Scars or Iron Hands they still have the numbers game on their side.
In game,>best fleet
Star Phantom's reserve rules are fantastic and good for lots of drop pods.>best guns
Overall the Imperial Fists because the vast majority of Space Marines are bolters an the IF chapter tactics improve just those.>most vehicles
White Scars by far. A Scarblade Strike Force can have EVERYONE on either Bikes or Land Speeders.