ESTA and dual nationality

I'm travelling to the US at the end of the month. Last time I was in the US was 2017 and for ESTA I used my Spanish passport. Last year I became British citizen.
Not sure which passport to use to enter the US now, if the Spanish one I used before or the British one. I live in the UK so I'd rather carry just one passport on my trip but since I have entered the US with the Spanish one before not sure if using another I will have any issues with my application. I know I have to declare if I have another nationality either way but I just want to carry one passport if possible

Use spanish passport if ESTA is still valid, otherwise get new esta on british passport

I used my British passport and no problem . Approved within an hour .
My previous ESTA expired 2 years ago