id go for the korg one personally
I would just buy one of the cheap Korgs (the Chromatic if you know music thoery well enough and change tunings, otherwise the standard one). Considering the cheap ones work, I would imagine either of those should work fine. If you are going to use it to tune on stage (which is really the only reason, I can think of, to get one of those), then see which one you can see the display better. Both are reputable brands after all.
I'm tempted to say the Korg. The display looks like it would be more visible and a lot clearer on stage.
I've got the boss and have been giging with it for the best part of 4 years now, works great, tunes accurately enough for me. And the display is really easy to see on a stage in any light. people moan about its bypass, but for the job it does, its fine. I doubt there's that much different in the circuitry of them either if im honest. I've got the boss, I'm happy with it, and would recommend it.