...The one I keep coming back to ...is the inexpensive Korg CA30 pictured above. They're cheap enough and small enough to have one with each instrument so you don't have to fuss about it, just get on with it.
Agree about the CA30 but "get on with it?" Are we boring you?

Obviously, I have a CA30 but the necessity to plug in my pickup under real-world gigging situations led me to want a clip-on.
the turbo tuner is far more accurate than the than the peterson strobo tuners the turbo tuner is .02 of a percent accurate compared with .1 and and petersons only truly an artificial strobe tuner. The ST-122 has a mic build in to pick up acoustic instruments and their customer services has been stellar if i ever had a question. i would not rule out the turbo tuner and they are less expensive then petersens along with being more accurate.
The Turbo Tuner ST-122 is not a clip-on, and is $129.99. It's not less expensive at all. It's almost twice the price of a StroboClip. If you delve into how it works, then you'll find that it offers no more of a "real" stroboscopic display than does the Peterson. Both electronically derive a "moving" display from an error signal within the device. The Turbo Tuner certainly does claim impressive accuracy. Let's take a look at what this means:
A440
StroboClip error: +/- 0.0254 Hz
ST-122 error: +/- 0.00050 Hz
Both are below the capability of any human to resolve. Let's say that you're worried about matching the beat frequencies across two strings. We'll take an extreme example for the double bass by letting the
fundamental, or first harmonic, be the octave above the open G. That's 196 Hz. The error on the StroboClip will be 0.0113 Hz. The fourth harmonic of that stopped (or harmonic) G is 784 Hz and it's error against the same overtone of string tuned perfectly would be 0.0452 Hz. That is, the fourth harmonic would "beat" against another perfectly tuned string at about 5/100 of a cycle! With the ST-122, the beat rate would be 0.0090 Hz or 9/1000 of a cycle.
So, for the double bass this is really all pretty silly. It's silly for other instruments as well when you consider that no acoustic instrument is even going to hold tuning within these limits and that the variance produced by the tuning adjusters on such instruments being adjusted by human hands swamps the accuracy of either of these tuners.
So, if you want a super-precise, super-accurate clip-on tuner, IMO, the StroboClip is the way to go. Especially for double-bass players (this IS a DB forum, after all), I see absolutely no practical reason to get the ST-122. For that matter, if you're willing to use a microphone-based tuner with the only other input option being a jack, then there are several options costing far less than the ST-122 that would provide more than adequate accuracy for the real world.