Gnar and Ekko have the same passive, but Gnar's is better.
Gnar MINI GNAR - PASSIVE: Every Hyper 2.png third attack or ability on the same target deals bonus magic damage (capped against monsters) and grants Gnar 30 / 45 / 60 / 75% bonus movement speed that decays over 3 seconds. 「 BONUS MAGIC DAMAGE: 10 / 20 / 30 / 40 / 50 (+ 6 / 8 / 10 / 12 / 14% of target's maximum health) 」 (+ 100% AP)
Ekko's basic attacks and damaging abilities apply Z-Drive Resonance to affected enemies for 4 seconds, stacking up to 3 times. At 3 stacks, Z-Drive Resonance is consumed to deal 30 - 140 (based on level) (+ 80% AP) magic damage to the target. Against enemy champions, Ekko also gains Z-Drive Resonance 2 50 / 60 / 70 / 80% bonus movement speed for 2 / 2.5 / 3 seconds. Z-Drive Resonance cannot affect the same target more than once every 5 seconds.
PASSIVE: Ekko's basic attacks deal 3% (+ 3% per 100 AP) of the target's missing health bonus magic damage to targets below 30% of their maximum health. The damage has a minimum threshold of 15 and is capped at 150 against minions and monsters.
K so Gnar's W passive deals 10+100% AP damage to the target + 6% of their maximum health as magic damage, rank 1 every 3 hits, and gives him 30% movement speed decaying over 3 seconds. and has no delay.
Ekko's ACTUAL passive gives him 30+80% AP +50% movement speed for 2 seconds every 5 seconds against the same target.
His W passive makes his basic attacks deal 3% + 3% per 100 AP of the target's missing health as bonus magic damage IF they're below 30% of their max HP.
So Gnar: 10+100% AP + 6% max health and 30% move speed for 3 seconds, can be used with no delay.
Ekko 30+80% AP + 3% + 3% per 100 AP missing health and 50% move speed for 2 seconds
Let's give Gnar and Ekko both 100 AP(and assume Gnar is going AP because obviously he usually doesn't).
Gnar: 10+100+6% max health and 30% move speed for 3 seconds. Ekko: 30+80+6% missing health(only if the target is below 30% HP) and 50% move speed for 2 seconds.
Make it against a target with 1000 HP. Gnar: 170 damage, can continue proccing it. Ekko: 110 damage, has to wait 5 seconds to proc it again.
For the sake of an example I'll give both of them 1 second attack speed.
It'll take Ekko 10 passive procs to kill the target. That's 80 seconds assuming you were only using the passive proc.
It'll take Gnar 6 passive procs to kill the target. That's 18 seconds assuming you were only using the passive proc.
I suppose at 30% health(after 7 passive procs) Ekko could go a little faster, but that's too complicated and Gnar would still win, I mean he only takes 18 seconds vs Ekko's somewhat 80 seconds(Even if you were to shave off seconds for Ekko's W passive, it'd only be like 10 or so seconds, definitely not 62).
This is ignoring other factors obviously, but I thought it was kind of interesting. I kinda wish I owned Gnar now so I could try some meta breaking AP Gnar.
