Start with the original

Hartnell.The show has changed its format several times, but the original vision was made in the Hartnell era. Later eras would adapt the format, but the first year or two are pretty much the most innovative, since they created all that has been taken for granted since.The Tom Baker era is the most popular, and offers a lot of innovations as well.Pretty much ALL eras have their innovations and great points (no argument), but if I was a newbie, I'd want to see the show from the beginning and see how it grew, developed, and changed over the passage of time.