I did a test on this a couple weeks ago. What I found was that the chinese models were far better than API rates, but about comparable on price vs the subsidized subcription model (chatgpt). Also it was my experience that codex completed tasks quicker.
That said, it's my best understanding that these american companies aren't profitable and will eventually raise rates (the old uber trick) so I'm keeping myself ready to switch when that day comes.
I keep a spreadsheet that estimates actual value (dollar amount per token per month, per subscription rate limit) and open weights are basically always cheaper than frontier weights. Recently things like GPT 5.6 Luna finally got the frontier close to the value of open weights but their limits keep them behind.