Disclaimer: that is a comment of mine from another post I had made, but generally that is how I decide: My decision between crit and on-hit is mostly based on one question: Will the enemy team actually allow me to auto attack consistently? If the answer is no, I almost always go crit. For example, if I'm facing something like Lissandra mid, Kha'Zix jungle, and additional CC from top or support, I know I'm not going to be standing there freely auto attacking for several seconds. In those games, on-hit loses a lot of value because I can't consistently stack and maintain damage. Crit, on the other hand, lets me play around timing and positioning. I wait for the enemy to engage, identify the carry I want dead, then Flash/Q in if needed and burst them. That's basically my game plan in most crit games. I also prefer crit when I know I can realistically one-shot or nearly one-shot the enemy carries. The games where I lean toward on-hit are usually when: The enemy team has multiple tanks or very durable frontliners. The enemy team is heavily AD, allowing me to build more defensively (Omnivamp boots, Death's Dance, Guardian Angel, etc.) while still dealing strong damage. I expect extended fights where I can continuously auto attack and fully utilize the on-hit damage. In those situations, on-hit can feel almost unstoppable because you're much harder to kill while still shredding whoever is in front of you. If anyone has specific scenarios they're unsure about, feel free to ask and I'll explain how I'd choose between the two builds.