I really like seeing articles or papers that describe the current advances and open challenges in a sub-field (such as [0]). They're underappreciated, but good practice or reading for folks wanting to get in the field. They're also worthwhile and humbling to look back at every few years: did we get the challenges right? How well did we understand the problem at the time?

0: https://arxiv.org/abs/1912.04977