I’m working on setting up my dusted-off guitar and bass and for intonation I need a better quality tuner then the Korg GT-3 I have. Which ones will help with the intonation? One that shows how much any note is off, not just the one of the open string.
Cheapest thing to try is probably apps for your phone or tablet. If you find a usable one, you’ll always have a free backup tuner to use.
I like Peterson strobe type tuners myself and either use mine or, more likely, just the high frets (tune a note on a lower string or even an external sound to a harmonic and then compare to same fretted note and adjust until both pairs match) to set intonation. Neither quantifies the error, but I don’t really care about the numbers.