No spoken words
Blue Crack Supplier
Well, I'd recommend starting with the man who took the show into the stratosphere, and has long been the audience favorite, Tom Baker. He played the role for seven years, and went through several companions, script editors, and show-runners, so there's a decent range of stuff from his era.
As far as what is available on DVD, I'd probably start with these, all of them rated very high by most fans:
1. The Pyramids of Mars
Great script, the best companion (journalist Sarah Jane Smith), some creepy villains, and a decent amount of on-location film to balance the soundstage video stuff.
2. The Talons of Weng-Chiang
Victorian-era London period epic and homage to Sherlock Holmes from the man considered the show's best script writer, Robert Holmes. Companion here is the savage warrior Leela.
3. The Robots of Death
A good murder whodunnit in Isaac Asimov territory, with some additional influence from Dune. Again, with Leela.
4. The Ark in Space
One of the highest viewer-ratings in the show's history, kind of an Alien vibe, stuck on a space station with a predator on the loose. Also from Robert Holmes and with companion Sarah Jane Smith.
5. City of Death
Co-written by Douglas Adams (of Hitchhiker's Guide fame), shot on location in Paris, and one of the most flat-out entertaining (and funny) stories ever. John Cleese cameos, as does Leonardo Da Vinci, and the companion this time is fellow Time Lord and genius Romana.
6. The Leisure Hive
This last one isn't actually a big fan favorite but to me it's pretty hard sci-fi and one of the more interesting stories from the late, moodier period of this Doctor. Companion again is Romana.
Anyway, pick one or two that sound the most interesting and see what happens. Key thing to remember is that these are mostly shot on video and look cheap as all hell, with dodgy special effects. Of course this is something Survivors shares (though it has more location work on film) and Blake's 7 looks even cheesier (and was on air around the same time). It's really about Tom Baker and the writing. If for some reason you can't get into Baker, the guy before him (Jon Pertwee) is older and a bit more of a serious action guy, and the one after (Peter Davison) is younger and more sympathetic. Though I'd probably just tell you to skip ahead to the new series.
This is perfect, thanks.