I like first sentences to snap.
But I'm not religious about it. I'm resistant to hard-and-fast rules about creative processes and much more focused on creating interesting subject matter, a clear, readable narrative flow, and a last sentence that pulls the threads tight or leaves the reader with a lasting impression.
The other day I saw "Lists of the Best Sentences — Opening, Closing, and Otherwise — in English-Language Novels" at openculture.com, and found myself pulled in.
Included in the piece were links to The American Scholar's ten best sentences, 22 authors' favorite first lines, as well as the 100 best first—and last—lines in fiction, according to the American Book Review.
Though I haven't read these books in years, the opening sentences in Anna Karenina, Lolita, Ulysses, Waiting for the Barbarians, and Moby Dick had a familiar sparkle and impressed me all over again with their staying power (particularly "Call me Ishmael" from Moby Dick, a three-word sentence which has lasted over 160 years).
I can't say I was converted to the cult of the opening line, but reviewing these beautiful and timeless sentences was pleasurable, and it did give me something to think about.