WIKIPEDIA
Although it has a rather simple design, there is a harmony between the fonts used.
We notice a serif font in the titles with a combination of sans-serif in the texts. It passes the feeling of seriousness but without great rigor.
UBER
Along the page you will notice a great rythm vertical layout, and always with the use of sans-serif letter giving a warm feeling. There is also an ideal size of x-height, which makes it more comfortable to read.
GUARDIAN
As it intends to show accuracy in the information, we can see the use of a serif source, which transmits this confidence to the reader. There is also a good vertical rythm as well as a proportional line-height.