I started using Codex 5.3. Compare to Opus 4.6, it's more precise in pinning down bugs and more concise with code. Opus can be best described as distracted and easily agreeable. Codex actually digs deeper for root causes and push back when I'm wrong.
Apple really needs to decouple swift debug and profiling tools from Xcode. I've been using vscode for swift work but hate having to switch back to Xcode for the tools.