I have probably at least one version of every guide out there!
My favorite is the Passporter because it has glimpses of everything in it, and it's easy to read. It has maps of each resort and park, and I like that it has ratings of the attractions from the authors and a child. It's also very practical with spaces to write confirmations and pockets to put itineraries and tickets. It's also nice that they have a website with updated information.
I like the Unofficial Guide too, but it is a bit wordy for some people (not as visually appealing as some other guides). I've heard of people who've followed their touring plans and thought they worked well, but I personally haven't used them.
I bought Birnbaums a couple of times, but since it is the "Official" guide, you won't find the "brutally honest" opinions you'll find in the other guides. I do agree that it's good for pictures and to get a good idea of what's in the parks if you've never been or haven't been for a long time.
I had one guide a while ago, WDW for Couples, which I really liked, but it looks like it hasn't been updated in a long time. I mostly liked that one for the restaurant reviews.
If you can afford it, I'd pick up 2-3 guides since they all have different things to offer.