Of the hundreds of millions of websites, one of the absolute best is clearly alhatorah.org. An incredibly helpful resource which I use endlessly [together with shas.alhatorah.org, rambam.alhatorah.org etc.]. A massive, colossal amount of work goes into these sites and they are constantly being updated and improved.
The problem is that many of us want to learn Torah with Yiras Shomayim and Emunah. To this end, it is troubling how many sources that are featured on this site were written by maskilim who were outsiders of the traditional Torah camp and have no place in the Beis Medrash. One such example is the commentary of M.D. Cassuto. It is actually assur to learn from people who don't believe in תורה מן השמים and to learn commentaries that subscribe to Kfirah. [See the sefer בינה ודעת עמ' ק-ק"א for sources and a very, very important sefer on the topic called "הרחק מעליה"]. [It goes w/o saying that another very helpful resource called "sefaria" also has Kfirah intermingled with the Torah, ה' ישמור!].
