It depends on what you do with the notes, if you want to quick entry notes or do you want to manage complex notes etc.
I would always recommend
OneNote, which is really the best notes and note taking app! And it's completely free
You can use it to create easy and fast food formatted notes but also for big and complex notes.
I personally use it for almost everything, for study, as a cookbook with recipes, as a review book, log and lot more.
There are also Apps for Windows and Mac to view and edit the stuff on PC/laptop
The sync is also very fast and good
If you want to have written notes with a stylus then I would recommend GoodNotes where you can create awesome notes. These notes are also indexed and you can search in your handwritten notes and can also convert your handwritten text to digital text and can export it to other apps, too.
You can also combine these 2 and use GoodNotes for handwritten notes and put the files in
OneNote where you can open the file in all systems, like on iPhone/iPod/iPad, laptop, android devices, windows devices etc.
If you have any questions then don't hesitate to ask
OneNote (iPhone):
https://appsto.re/de/UjIDy.i
(There's also an iPad app which offers more features)
GoodNotes:
https://appsto.re/de/zjwAU.i