My favorite episodes since the revival tend to be Moffat-penned ones like "Blink" and "Midnight" that use only a few characters and sparse sets.
"Midnight" is actually written by Davies, but, yes, both of those episodes are among the very best.
Its a bit expensive if you want to buy old serials on DVD (because I don't like the quality of episodes available online). My local Barnes & Noble has my favorite serial, "City of Death" (co-written by Douglas Adams and one of the most popular Fourth Doctor serials), but it will set me back some $30 last time I looked.
I just watched "City of Death" last week streaming on Netflix.
David Tennant was an excellent Doctor (and since he was a fan since he was young, he knew exactly how he wanted to play that character), but I've been extremely impressed by Matt Smith, the new Doctor (early promo photos had me worried that he'd be played as a brooding emo-y Doctor, but instead we've gotten a Doctor that's actually more zany than Tennant's Tenth).
I've only seen three of the Matt Smith ones so far, but I like what I've seen. I just ordered the season five DVD set a couple days ago.