Benjamin Olson
Hero
Greenflame blade uses a melee attack so you can sneak attack or smite with it. I've always been confised as to the attraction to Booming blade. More damage if you move? Hard to visualize. IMHO
The draws of Booming Blade over Green Flame Blade are that: 1) There won't always be someone next to the target, but d8s will always be bigger than d6s, 2) Fire resistance is a lot more common than Thunder resistance, 3) for those people who have it and some sort of easy disengage (like an Arcane Trickster) it makes their disengaging seem more awesome, 4) I don't have to deal with the DM who says "oh, but the only other creature next to the target is you" (RAI you can choose to have it go nowhere, but still it's a worry), and finally 5) I can theorycraft an elaborate character build around how I'm going to be disengaging all over the place more easily than I can theorycraft around how I'm going to make my enemies always clump right next to each other.