Darius has more range, more health, more AD, and more defenses than Poppy
How is a fighter allowed to be tankier than a tank, with longer range of engagement and more damage, all while only having to build a single item to invalidate anything his opponent can buy?
Buying any armor just makes his 
more gold efficient while throwing away gold of your own, meaning he'll outtrade you until he can ult you from 1/3 health.
You can't buy damage to outdamage him because even at 350 AD, he still deals more at just 290.
Remove total AD scaling from the game on everything but actual basic attack modifiers. If you want to scale with AD you should actually have to buy AD. It's bad enough this cancer character has one of the highest banrates in the game from his obnoxious gameplay, it's all the worse when there is no counterplay outside of "hope you don't have to first pick top so you can pick a ranged character against him."
Every time I lane against this fucker all I can think is "Man it sure would be great if my Q healed me" "Man it sure would be great if I could rip an opponent under my turret/out of theirs from beyond their attack range" "Man it sure would be great if my Ult just deleted people instead of sending them twenty feet back while tickling their nads" "Man it sure would be great if I could build a single item that has no counterbuild."
or 
.
lately though so I'm not all too sure...
+ Aftershock you could be a strong tank threat, but if you miss your E you are done-zo. Grasp is not worth. Sorcery is def no-no as a primary. Secondary Celerity + Manaband/Scorch would let you trade way better in lane, but overall only Celerity is worth. Inspiration... is interesting but gimmicky. Darius would only really get Magic Boots. Biscuit Delivery could cause you to win a fight and snowball, but that's too cheese.
it would probably be:
swap one of these out with either RG or BotrK, depending on whether you don't need engage or sticking power.
probably has an easier time to get onto people with her e (maybe longer range than his e) and the w ms buff. Also, poppy has a ton of burst if you go 
. Probably the main difference is how darius is only there to tank a little and do damage while poppy can peal and dive for a good amount of burst damage.
every time for the q sheen spam
as that'll give you very strong burst + CDR. Then again you could always build both Trinity + Titanic into tank and be even more annoying lol, but that depends on team comp (or if you had another tank/off-tank to help back up the loss of defensive stats).
gets both of those and it's scary...
You won't lose this lane, you just q him if he all ins you E W away you can get a kill early so you can rush sorcerer boots to kite/chase easily after that you will want to rush Liandrys because most rush black cleaver even when losing. trust me I haven't lost against a darius as Vladimir before preseason Especially now.
Not only you are stupid tanky more tanky than darius you do a trillion dmg, if he had already w'd and he's about to q you go inside don't make him hit you with the blade or else he won the trade/possibly kill you but long as you land your e with 3 minions of urs + your ult you will win easily.
from what I've seen these champions has had a huge successful in laning against darius. I would mention Swain he was a good pick against darius aswel before preseason but RIP Deathfire touch.