TOD - Episodes
This is absolutely impossible!
Doctor Who has thirteen episodes per season, it is impossible to narrow the best down to ten!

More seriously, that series had some of it's best stories over the past year. The best of the lot was
Blink, a time-travel sci-fi/horror story filled with "wibbly-wobbly, timey-wimey" stuff, made even more remarkable in that it was a) told from the p.o.v. of someone who was
not jumping around in time, but witnessing it happening to the people around her, and b) involved the Doctor and Martha minimally. Brilliant writing.
Another episode,
Gridlock was also very good, and fun, while demonstating the positive effects of faith. And the two-parter,
Human Nature and
The Family of Blood, gave a chilling example of what war's effects can be, not by being anti-war but by showing how different real war is to the glorification it gets by those not involved directly.
I'm trying to think of any other series that had individual episodes that really stuck. Nope, not happening.