In my mind there are three tiers:

The SOTA: Fable, GPT 5.6 Sol, Opus 5

The "enterprise admin did not turn on the new models": Opus 4.8, GPT 5.5

The "I love hallucinated garbage": Sonnet, Qwen 3.6, GPT 5.4 mini, GPT 5.3 Codex, etc.

Results vary widely

What did your tiers consist of when GPT 5.3 was the latest?

I believe I was still using Opus 4.6 with the Claude Code CLI.

Before that, Gemini 3 Pro in Antigravity.

I have no experience with GPT 5.3 beyond seeing the nightmares colleagues produced in their MRs with GPT 5.3 Codex. It could be that they had the distilled 5.3 Codex Spark selected, I am not sure.

Obviously no. There is also a significant capability difference e.g. between Opus 4.8 and Fable.