This is my go-to for recording audio. It's small but packed with features like dual recording to make sure you never peak out your audio as well as auto leveling that has never failed me. Use this for interviews, my own gear reviews for YT and have friends who love it for weddings.

Official Tascam write-up:
Run-and-gun filmmakers will appreciate its ultra-compact form factor and power-up-and-record workflow for time-sensitive shoots. There's no need to select inputs, arm tracks, or choose channel modes. Clip the DR-10L to a belt, or stash it in a pocket, start recording, and let it roll for the rest of the day. A single AAA battery will keep it running for up to 10 hours, so all-day gigs won't be a problem. Power the DR-10L via USB if you need indefinite operating time for sessions that continue on into the night. Worried about clipping? Don't be. The DR-10L's limiter and auto-level functions work to prevent overloading, while the dual-recording feature makes a safety track at a lower level, just in case.