Maybe start with the rebooted episodes with Christopher Eccleston (the ninth Doctor). Not only are the episodes generally well-written, with excellent performances, but it does a good job introducing you to the universe of Doctor Who. It's where I started, thanks to PBS. My first ep was one near the end, I had no idea what was going on, and yet I still loved it enough to still be watching now.
Actually the only reason I liked Spyfall at all was
But I'm not wrong when I say the best eps at that point had Chibnall involved. (Yes, yes, my opinion.) The writing really, REALLY needs work. I mean, holy crap, over all it's worse than last season, and that was pretty bad!
As an aside, the latest ep was good, the ghost story one, but I need to watch it again because I originally watched in sub-optimal conditions.
Um, actually, I was at a Doctor Who convention last weekend in Los Angeles. Got to meet Christopher Eccleston and Pearl Mackie among others. They showed the latest episode an hour earlier than BBC America, in a crowded room, on a big screen, with morons wooing and clapping when you're trying to hear the dialogue, which is why I need to rewatch it...