What I like about PDF Expert, is that it's emphasized on pdf annotation. As an example: your annotations are nicely listed in a separate dropdown. Something else I use daily is a sync to a folder on google drive, allowing me to annotate documents online without downloading them to my device.
At least one bonus is also that you can create pdf documents.
So if you focus heavily and exclusively on pdf annotating, I think PD Expert is a very good option.
However, depending on your needs, a note taking app might fit the bill just as well. I use GoodNotes myself to do quite some pdf annotating, and as a bonus having other functionalities that are slightly more emphasized on hand writing and sketching.
Thanks for taking the time to reply. So since I have an iPad Air 2 (with no support for Apple Pencil), can I highlight text in PDFs and bookmark items with my finger? Or is Apple Pencil required for PDF Expert to work for basic highlighting? My edits/highlights are saved into the PDF so I can open it on a different device? Thank you.
I second PDF Expert. Another very nice feature not mentioned is continiuous vertical scroll. This is very handy when reading and annotating, especially when zoomed in.
Vertical scrolling is indeed handy when reading, not so sure when annotating. I often find myself scrolling by accidentally resting my handpalm on the screen while handwriting or sketching on the page (I am right handed).