I'm puzzled at the moment with which one to choose.

• Form-factor plays a significant role in my project, so I prefer the smaller boards mentioned in the title to fuller boards like the UNO, MEGA, etc.
• I have an RC522 RFID read/write module and would like to use it without having to deal with level switching, as the RFID module requires 3.3V.

What can you advise?

Thank you in advance!