Decline bench and dips with arched back.
Is it better to hit tri's with chest? I typically to bi's and tri's on the same day.
It's not about better or worse universally, it's about finding what works best for YOU. I have hit tris with bis for many years, and also hit tris with chest, tris with delts, tris with back. Each has it's pros and cons. Experiment to see what gives you the best results.