Opus 4.5 is significantly better if you can afford it. They also recently lowered the price for Opus 4.5, so it is only 1.67x the price of Sonnet, instead of 5

Opus 4.5 is significantly better if you can afford it. They also recently lowered the price for Opus 4.5, so it is only 1.67x the price of Sonnet, instead of 5x for Opus 4.