It's simple, but configurable tool. With built-in player and easy navigation.
FLAC files have quality of WAV file, but with just ~50% size.

Features:
★ Supported frequencies (Hz): 8000, 11025, 16000, 22050, 44100, 48000, 88200, 96000.
★ Simple to use, configuration is optional.
★ Formats: FLAC (default), WAV, AAC / MP4 / M4A.
★ Source selection: default, mic, unprocessed, etc.
★ Automatic date-based recording name (can be always changed).
★ Ability to pause recording.
★ Can be controlled from the notifications / lock screen (if device supports it).
★ Save on internal or external storage.
★ Built-in player.
★ Mono / stereo support.

How to:
*) Press big button with microphone to start recording.
*) Click 'stop' button when you want to finish recording. You can also make breaks in recording by clicking pause button.
*) Recording settings can be changed while playing, however some options will make recorder to finish current file and record audio to new file (because many formats can't change configuration mid-stream).
*) Recording can be played directly from the same screen or from the 'list' screen.
*) You can also share / open your recording in other apps by using 'more' button on the 'list' screen.

Ads:
May be easily ignored if you don't want to support this app.
They can be removed with in-app-purchase.