I just ban Renekton TBH.
He's a terribly designed champion IMO. The whole purpose of him is to screw over the enemy laner with his early dominance and massive level 6 powerspike. As you transition to teamfights, he loses 99 percent of his viability and becomes a 2500 health meat shield, making both you and the enemy Renekton useless since you'll be behind. The design is really stupid IMO, but again, some of you may disagree and I respect that.
But as much as people say it, I'll say it again; Garen is a pretty straight forward matchup AS LONG as you don't get hit by his E. If you stay in its range, you'll start to see your health drop frighteningly fast no matter what champion you are in lane. Without that though, he really has no means to kill you. Even if his silence is up, you can still all in him most of the time. Even at level 6, the only time he'll be able to kill most bruisers is with some Silence+E+R+Ignite cheese.
Darius hard counters his kit, and if you let Garen push your tower Level 3, you can AA --> W cancel --> AA (At this point Garens will start to retreat) --> E pull him back --> Q (Your 5 stacks of hemmorage will AT LEAST cause him to panic flash). Close the flash gap, run him down with ghost, and kill him. You've one lane at that point as long as you push that wave back to his tower.
Again, Garen's E is arguably more dangerous then his ultimate. This sets up the damage to even be able to execute.
If you let Garen hit you with his abilities, he's going to chunk you out. Even if he does, the least you can do is make sure he chunks your minions out at the same time forcing a push. If you play behind minions, respect a reasonable gap between you two, and put up an equal dominance, there shouldn't be a reason for you being behind.
Edit: And honestly, the few times I've played Garen wasn't because he's the best pick in the game; it's because he's hella fun to play. Execute a champion, and watch the visual ripple of the screen as Garen booms, "DEMACIA!" And you'll see why he's so satisfying to play.