Rose. For better or worse, it definitely feels like all of Doctor Who distilled into a single episode, in addition to being the first New Who episode and establishing the core themes and concepts well. The Doctor being mysterious and charismatic, the feelings of adventure, the great character moments and thought-provoking concepts, and yes, that the show is often incredibly hokey.
I kind sort of just think that Doctor Who isn't for everyone, and I promise I don't mean that in a gatekeeping way. Different eras resonate more than others, and that's awesome, but most of New Who has the same campy DNA. Some people will find the camp and low-budget effects endearing, some will be completely turned off by it and stop watching, and others will be willing to look past it because they're sold on everything else.
There's some good one-shot episodes that probably don't do a good job representing what Doctor Who is, warts and all, or in a ways that establish continuity and theme. I've known quite a few people in my day who were introduced famous self-contained episodes, but then fall off quick after trying to watch the show.