Assuming we are talking about Code/Codex are you on API billing or subscription? I have essentially unlimited API billing at my disposal and I haven't noticed any degradation of quality across Opus versions.
I also don’t have time to do much personal coding outside of work, so I haven’t subscribed to a personal one yet. But I intend to go for Codex just to balance the Claude at work and also because of the hostile moves from Anthropic toward their consumer business.