Just upfront, hopefully not here (you never know) but definitely elsewhere, you're going to run into a lot of the usual bigots telling you that DOctor wHO EnDED wiTH cApaLDi. Coincidentally, the end of Capaldi's run basically dovetails with when social media algorithms started giving these people brain worms, so everything after that is wOkE gArBaGe while everything before it, with exactly the same messages and techniques, is galaxy brain stuff. They can't deal with a woman or Black man being on screen so just ignore them, please. (That said, the Thirteenth Doctor's run is...not great, but certainly not because of those reasons.) If you are concerned about things like a "woke agenda" then Doctor Who is very, very much not the show for you - this has been an important part of the show's DNA since the 60s.
I've loved Doctor Who for thirty years, and seen nearly every episode of every Doctor. The thing about Doctor Who is that it's goofy and campy, and that ends up with it being dated sometimes, sometimes moreso than other shows. This isn't a bad thing! It's charming and fun, but depending on the kind of viewer you are, that might mean that you want to start with the current series (it's loads of fun and the current Doctor and companion are exceptional), and then watch the older ones in context.
However, that's going to get you only about six episodes so far. If you really want a project, I'd say start with the 2005 series (the Ninth Doctor) and go from there. You're going to run into quite a bit that's very early 2000s, but the fun, camp, and drama, are all on display. I know others will say you can start with the first series of the Eleventh Doctor, but to me you'll run into a really turgid arc of the showrunner tediously and self-referentially mystery boxing over and over far too soon. This is stuff you ignore when you've been watching for a while (or can skip) but it might demoralize you to get into it and then get to molasses so soon.
The classic series are very different - not in terms of story, but format. I love them, I started with the Fourth Doctor, but it's not to everyone's taste. They are shorter arcs or four or six twenty-minute episodes, with drastically lower production values and slower pacing. One of the best stories involves the Doctor fighting essentially spray-painted green bubble wrap on a set that sort of looks like a bathroom. If you're up for it, it's wonderful, but it's very different visually and structurally than modern shows.