Well, VoxeLibre (formerly Mineclone 2) is not quite feature complete compared to the latest Minecraft release. It’s got feature parity more-or-less up to 1.12 but a few odds and ends are incomplete or behave differently from vanilla Minecraft in subtle ways. I expect the situation to improve over time.
I will say that Minetest’s performance is loads better than Java OG Minecraft. Night and day.