Claude 3.7 and 4 are better for me than Gemini 2.5 for vibing with legacy code. Gemini 2.5 has some great solutions if you handhold it, but tends to make too many assumptions about what would be better which can tear things up as an agent, imo. In other words, Gemini is smarter, but less practical when working with existing code, from what I’ve experienced. To each their own, though.