Personalization: How Necessary is it really?

As I've been sitting here, working on my query letter, I was thinking about the personalization part and wondering just how important it really is.

If you follow Janet Reid's QueryShark blog, every time someone puts a bit in about how they chose her as an agent, she snips it out.  She knows who she represents.  She knows what she represents.  She expects people querying her have already done their research and wouldn't be querying her unless they met her needs.

But you always hear about how important it is to put that personalization in there.

Right now, my query sits at 219 words (subject to change) - most of which is the story.  I've got a line with the word count, title and genre.  I don't have anything about me, because... well let's face it, I have no creds to put in a query letter.  That leaves roughly 31 words to talk about why I chose the agent.

Ummm, after 6 years, I don't remember what in particular made me chose the agents I have on my short list.  Mostly it's their blogs, or some interview I read years ago that I couldn't find again if I tried.  I've queried Jessica Faust because, well, she's Jessica Faust.  She's always been pleasant in her communications, I like her blog and even when she's rejected me, she's been super-professional.  (And it doesn't hurt that she asked me to query her with future projects.)  But Jennifer Jackson.  Well, I query her because she's like Jim Butcher's agent and a rock star.  If she can do for me what she's done for him, I'll be in writerly nirvana.

I guess what it boils down to is falling back on the old maxim: Tailor your query to meet each agent's wants.  They want the personal touch, give it to them.  If not, don't.

What do you think?  How personal are your queries?