Viktor is pretty good. He doesn't fill a specific niche, but he isn't as weak as he's made out to be. He can choose to max either q or e in lane depending on matchup and at least in gold V to gold III he doesn't straight up lose games. His item taking up a slot is a 40 minute problem which doesn't come up that frequently aside from taking up an item slot and making it harder to complete items earlier on.
I think he's tier 2 or 3 at worst, but that's just imo.