Form-factor-wise, there are again three main types. Although some bass and uke-specific models exist, there should be no issues switching between instruments.
Microphone tuner (free-$/£10):  As these small, usually cheap tuners use a microphone for their input, they're flexible in terms of what source they can take. Great if you need to tune up many stringed instruments - but the trade-off is that they're susceptible to interference from background noise. When we were coming up, these were usually dedicated hardware boxes, but nowadays, they're just as likely to be an app on your phone.
Clip-on ($/£5-30): Clip-on guitar tuners attach to the headstock of the instrument and work via detecting vibrations. As a result, they can be very efficient in battery use, as well as small. The accuracy of clip-ons like the TC Polytune Clip and Unitune is now good enough that we've seen them used in professional studios, mostly due to their convenience. They can be kept near to hand, or scattered around so there's always a tuner within reach for when that great idea arrives.
Stompbox tuner ($/£50+): The third type is the stompbox. These take a standard 1/4" jack input to operate. This means that they will only work with electric guitars, basses, and ukuleles, or acoustic instruments with a pickup. In terms of signal path, this stompbox should normally go first in your signal chain, as it can be used to mute the guitar when in use. However, due to the use of buffers in many tuners, some players prefer to keep it out of the audio path. There are effect pedals with a dedicated tuner out so you can split your signal into a tuner mid-chain. This generally has been our preference, and means the tuner can be left 'always on.'
Rackmount tuner ($/£100+): The final type of tuner, usually found on professional touring rigs is the rackmount tuner. The main advantage of a rackmount tuner is the increased surface area which means you can get a far more accurate view of your guitar's tuning. The size is also a limitation, however, as it'll take up a lot of room on your pedalboard. If you already have a rackmount setup or you want one for your studio, then the rackmount tuner is the ultimate guitar tuner when it comes to accuracy.