Oh, one of the chargers is good, but I'm thinking of going all 3.3V instead of 5V. So I'd need an extra stage with the charger, making it about the same fuss as the bridge+cap+buck.

The buck board has adjustable output (multi-turn pot), so I can tune it nicely for exactly 3.3V output.

Still, the final choice will come once all of the pieces have arrived. The LCD I'm using wants 3.3V, the RTC is 3.3V, the temperature sensors don't care, and the ethernet adapter also wants 3.3V.

So I may as well just run the Atmega328p at 3.3V as well.

Cheers