Essence Reaver, however, is a stronger early-path than Bloodthirster is. It is actually surprisingly godlike at first power-spike. It gives you by far the most AD per gold out of all the ADC items, it gives you meaningful sustain whereas Bloodthirster is usually unnecessary, the CDR is okay but not as good as other stats for your role, and the mana regen is okay but not as good as other stats for your role. However, you get the most gold effectiveness with Essence Reaver. It gives you sub-optimal stats to coincide with gold-effeciency. Initially it is insanely strong.

The first issue with Essence Reaver 1st vs. Infinity Edge first is minor lack of auto-based damage after your second-item pick-up. This is less of an issue vs. Bloodthirster, however, Essence Reaver does significantly more damage than Bloodthirster per gold and you will notice this difference dramatically.

The biggest issue with Essence Reaver first, is the noticeable lack of late-game scaling (after 3-4 completed items.) Essence Reaver won't protect you anything like Bloodthirster will late-game, and the extra lifesteal and the lifesteal shield will scale more and more with each item.

Infinity Edge's damage will scale more and more with each item.

The thing is though, Infinity Edge usually builds into Bloodthirster 3rd or 4th item. And Bloodthirster builds into Infinity Edge 3rd or 4th item. Essence Reaver builds into Infinity Edge 3rd or 4th item, making the difference between the late-game builds only between Bloodthirster and Essence Reaver. The late-game difference ultimately gives the Essence Reaver the most damage late-game in all of these builds, but with less protection.