I just ordered a Polytune 2 for my board (arrives tomorrow). I've been using a PW Tru Strobe, which I'll keep as a backup. When I gig with my GT-100, I use the onboard tuner. For solo acoustic shows, I usually use a Snark headstock tuner.
Used a Peterson Strobostomp for years with great satisfaction.
But it ate up board real estate. Now have a Polytune Noir (black mini size) and so far so good.
Actually, it's nice to have the Strobostomp free to use for bench work i.e. setups as it's still the most accurate and able to show the slightest increments.
Around the home/studio it's a DeltaLab CT-30 clip-on (great display) or a Korg clip-on (not as good).
But, like so many others, my iPhone is usually close at hand and the Polytune app is admittedly fantastic. When you consider it's $5 for perfect (and accurate) port of their tuner, it's another piece of 'disruptive technology' that obviates the need for more bit$ and piece$.