Got my new iPad Air m2

After months of consideration and thinking of alternatives, went with iPad Air M2 in black Friday sale. One thing I found interesting was reading looks comfortable with iPad. Any good apps to read pdfs

And one thing probably I didn’t do much research into the app ecosystem is MS365 apps require subscription. Is there any good alternate for this.. the apple native apps like pages, numbers seem good but just want to hear out if there are other options

Battery seems decent. Display is good.

I am also a bit behind on the recommended or must try apps. Can you suggest some