I'm going to assume you have at least a passing familiarity with "Doctor Who" because - well, this is the internet after all (I mean, pick a random Tumblr and chances are about 90% that somewhere in the first page will be a Dr. Who gif...) Which is both a blessing and a curse for Dr. Who fandom, because while it's great to be part of a big community that spans continents, age ranges and genders, the truth is that online Dr. Who fandom can be quite the toxic cesspool.
I don't mean to denigrate all of Dr. Who fandom, after all, I am a founding member of both the St. Joseph, Missouri and New York City local Dr. Who fan groups, and many of my closest friends have come out of that association. But with a TV show that has lasted for as long as "Dr. Who" and has gone through as many changes through the years as it has, there are going to be few fans who can unequivocally say that they are fans of the entirety of the series. More likely, they are huge fans of certain eras, while being indifferent or even hostile to certain eras of the program.
I remember inviting my causal friend Nicole to one of our Dr. Who meet-up events, and she declined politely because she felt that she would feel left out because, although she liked David Tennant as the Doctor, she didn't care much for the new Doctor, Matt Smith. What she didn't realize was that didn't make her an outsider, that just put her in line with about half of all Dr. Who fandom who seem to take delight in bemoaning about how bad the show has gotten when compared to the glory years back when David Tennant was the Doctor (or Christopher Eccleston, or Peter Davison, or Tom Baker, etc.)
And fandom has always been that way with Dr. Who, whether it be the fanzine DWB bemoaning the travesty of the Colin Baker years in the Eighties, to the epic Third Doctor vs. the Seventh Doctor flamewars of rec.arts.drwho (which gave rise to the silliest of insults, calling anyone who had anything at all good to say about the seventh Doctor, Sylvester McCoy, a "Pro McCoy Troll"), to the "rad" vs. "trad" debates of the early 2000s (about which kind of stories people preferred, the traditional tales of alien invasion or the radical experiments that tried to bend the genre in strange new ways). Fans love the series in general, but many of them also hate huge swathes of it with the intensity of a thousand suns. And online, this gets magnified and and can get quite annoying and tiring.
Which is why I prefer interacting with other fans the old fashioned way, in person. The Dr. Who group I meet with (dwny.org) has its meetings at a pub, which is quite appropriate because what better place can you think of to go hear people talking utter bollocks? At the pub, a proclamation like "Colin Baker's first season is objectively better than the current Matt Smith series" can be taken in its proper context, not as a sober, reflective Facebook post about the relative quality of both eras but rather as an affectionate wind-up given by someone who may have had one too many pints.
But lest you think I am excepting myself from criticism, I'll be the first to admit that I can talk as much bollocks as the next guy - that's what makes fandom attractive for me. I mean, where else can you have these debates? Just because. in the grand scheme of things, the relative merits of "Timelash" is probably near the bottom of things that actually matter, they still have a lot of personal meaning to a great deal of us. And even if the people who you encounter are completely wrong about the brilliance of Paul Darrow's post-modern Richard III performance as "Tekker", it's still fun to have the discussion. And if fandom isn't fun, then why bother?