My reference in terms of tuner for over 20 years, the Boss TU 12.
I do not claim it to be the best, but as he never gave me and it works perfectly still ...
For 4 or 5 years, I use tuners clip to clip on the fretboard. Very handy on stage or in a hurry, because immediately accessible.
I tried different model and different brands, but still in the same price range (between 10 and 20 euros).
The result is not very accurate and two of them have already passed away. I return to my regular TU12.
And then I let myself tempted by the E-tuner Shadow.
I installed it on a Whale "whalebone55" and it works perfectly!
Small discrete but visible light; green when it's just red when this is false and green with gradual changes red when approaching the right note. it's very comfortable, very discreet and above all it is much more accurate than the tuner clips I usually use!
Installation is very simple: in twenty minutes, some turn of a screwdriver and two small welds.
For less than 25 euros (Thom. Of), it's not worth the trouble to deny it, this is a real bargain!
Otherwise, for reliability over time is 5 years warranty ... we'll see by then
I just regret not being able to install on my telecaster: the volume button is too close to the microphone, I would have to change or modify the pickguard.
When will a version for single coil?