Opus 5 is a regression from Anthropic. You need a lot of steering to get it work. It assumes, miss the instructions and fight with us on few occasions.
Fable 5 is good but exhaust quickly. No opinion but to use opus 4.8 again. Is everyone else experiencing the same
I got best of both worlds. Use codex plugin for code with Fable for planning and let Claude code use codex for exploration, implementation and with autoreview skill. It’s almost 90% ready to ship