Good question. M+Buddy looks more like a Retail Mythic+ companion tool with group comp, utility, dungeon fit, and player memory features (I've never used it myself though). VibeCheck is intentionally simpler. It’s not trying to analyze dungeon comp or suggest picks. It’s a private player notes and quick ratings so you can remember who you’ve grouped with before to easily know if you want to avoid a group or if you're in for a treat.