I keep playing both because they're really fun and interesting, but I'm just figuring stuff out on my own so I feel like I'm missing a lot of the finer details.
Honestly I feel kinda weird asking pro streamers live, so I tried looking for one-tricks...
seems like there aren't any ;;
There are totally dead champions like Kassadin, but there's no slightly dead champion like Neela, you know.
But Viktor though, why aren't there mains for him?
The Viktor next door 
The other (Va)nilla
There are quite a few Viktor players, but I've never seen anyone who specifically mains him, y'know.
More
but Baljepp's friend is the Nilah otp, you know
More
I heard Dopa's only playing Viktor these days.
More
He's not a Viktor one-trick or anything but out of everyone I've seen who plays him well (excluding Faker), it's Dopa.
More
viktors just a doofus
More
It's not that there aren't any one-tricks—it's just that they're popular, strong champs that a lot of good players play.
More
Chinese player 斗吧 Douba is actually insane on Big Oat
More
how we looking?
More