What are you asking about? "Just" about any old tuner?
Any/most of them are fine. I've mucked about with a lot over the years.
Clip on tuner? Probably any of them are fine. The advantage with them is that you can tune in a noisy room since it's picking up vibrations of the instrument it's clipped on to.
I'm not quite sure though, why I'm seeing so many guitars with tuners left on. Tuning is important. Obsessing about tuning isn't good. And, if your instrument can't stay in tune for the length of a playing session - maybe you need new tuners.
Apps? Guitar Tuna is fine. But my favourite is Tunable. That one is awesome. I'm not a tech person - and I don't use my phone, computer, tablet etc. for everything...but Tunable has become my go to.
I'd avoid pitch-pipes though. Have yet to find one that is actually in tune. Tuning forks however, if you can use them, are fine.
2016 Fender CN320AS
2018 Cordoba C10 crossover
2019? Peavey Composer
2018 Sawchyn Beavertail
1982ish Shiraki Mandolin
...and miscellaneous bits and pieces.