Garen is fine. If anything, they can rework his W, which they are. I prefer the flat 30 armor/magic resistance over the 20% bonus resistances. I prefer the longer auto attack range, the slight gap closer on Q, and the villain mechanic. I do not have to buy sun fire cape because the enemy picked up a hexdrinker.
I personally prefer the Garen rework. The 2.5 second silence was too long. I max Q anyways, so by the time I hit level 10, I am not that much behind from the old Garen spin damage of the early levels. I prefer the shred on E, so I do not have to buy Cleaver.
I would easily trade old Garen for the current one.
I do not buy cleaver or sunfire on Garen, but I have a 60% or so win rate on Garen in D5.
Learn to adapt your build and go at least 3 damage items, and you will see how strong Garen actually is.
But Garen gets kited! Good. He needs counter play and it separates the Great Garen players from the trash ones.
https://www.youtube.com/watch?v=9XDLzierYZg