Bigger screens are essential for scientific papers that have lots of charts and other figures. For eink-type screens there's not a lot type choose from. Fujitsu has a couple of A4 size models that look pretty good. If you can deal with traditional screens, the biggest iPad Pro is great.

Remarkable and some other companies have A5 or 10.3" screens but these are too small IMHO. You will still end up zooming and panning.