I'm going to weigh in favorably on SNARK for a couple of reasons:

1) Price. They are very inexpensive

2) They're clip-on, so you can use them for acoustic instruments too

3) some of my other tuners only show EBGDAE... which is great for guitar, but useless for other instruments or for special tunings. Snark reports all of the notes

4) some tuners are 'jumpy", meaning when you pluck a string, the display rapidly reports a bunch of different notes, maybe getting confused by harmonics. I've found the Snarks to be pretty stable in that way.

In summary, snark works on all my instruments, and its cheap enough to keep one (or two) in each instrument case. They have an on-off switch and they don't draw much current, so if you remember to turn it off after you tune, the batteries last a long time. They use a common battery that's found everywhere. I absolutely love these little tuners!

https://www.dropbox.com/sh/ey71h8ep047758h/AAC12jNM0Hz9Q8zsh5iDeqNHa?dl=0