My better half typed the list here, which I am shamelessly copying and pasting!
If you have favorites, leave them in the comments!
Angel in the Waters, Doman & Hatke: the most pro-life children's book of all time.
Click, Clack, Moo: Cows that Type, Cronin & Lewin: pure silliness. Sequels abound, too.
More Bugs in Boxes, Carter: how they did some of these pop-ups, I'll never know. Carter's other buggy pop-up books are also great.
Small Acts of Kindness, Vollbracht & Fay: a book about providence and the effects of free will.
Dinosaur Roar!, Stickland & Stickland: a favorite from ages 2-7, a remarkably wide range.
Night House, Bright House, Wellington: very creative rhymes and highly detailed, if cartoonish, pictures.
Jabberwocky, Carroll & Base: it's hard to beat Lewis Carroll for read-aloud, and Graeme Base is one of our favorite children's illustrators.
Animalia, Base: insanely (and beautifully) detailed, it's the only alphabet book I know of that can take 15-30 minutes to read (depending on attention span).
No Matter What, Gliori: this book about unconditional love helped Klenda through a rough spat of tantrums a few years back, and I'll always be grateful to Debi Gliori for that.
Mouse's Magic Paints: A First Book of Colors, Healey & Chamberlain: as creative as Harold and the Purple Crayon, only with a more solid plot and cast of characters.
Mouse Paint, Walsh: what is it about mice and colors?
When the Rooster Crowed, Lillie & Parker: one of the best farm animal books out there, it often gets read five times per sitting.
Dear Zoo, Rod Campbell: a very silly lift-a-flap book.
The Very Hungry Caterpillar, Carle: a classic. Personally, I don't get the appeal, but all five kids have loved it, so there must be something there.
Bears in the Night, Berenstain & Berenstain: I don't think much of the Berenstains' books for older kids, but their "Bright and Early" books make for wonderful read-alouds. Another one that can easily be read five times at a sitting.
Bears on Wheels, Berenstain & Berenstain: ditto.
Gorgeous!, Castle & Shields: a baby zebra wanders off from the hers and has an adventure. Favorite quote: "Little Zeb trotted off behind Big Zeb on his brand-new, clippy-cloppy, springy-zingy legs."
Too Much Talk, Medearis & Vitale: a little disturbing, but excellent, this adaptation of an African folk tale has a theme that will resonate with children who are tired of adults not believing them.
The Princess and the Kiss, Bishop & McDaniels: an allegory on purity for girls, but most boys like it too.
The Squire and the Scroll, Bishop & McDaniels: an allegory on purity for boys, but most girls like it too.
Day Dreams: An Imagination Book, Adams: A very clever hide-and-reveal die-cut book.
William and the Magic Ring: A Shadow Casting Bedtime Story, Robinson: unfortunately expensive, but if you can find it used, it's worth a look. (New, it comes with a flashlight.) You provide the blank wall for this shadow-casting story. If you're creative, you can even design your own special effects by moving the flashlight closer or farther away from the book, moving the book (and therefore the shadows) in a circle, etc.
In the Forest, Ets: a classic read-aloud, full of imagination. The most peaceful book Choclo enjoys.
A Day on the Farm, Hulick & Miller: my favorite of the "Little Golden Book" series. Not big on laughs, but the kids love it every time.
The Little Book, Horvath & Wilkin: my second-favorite "Little Golden Book," the clever rhymes and lovely pictures entrance kids ages 2-4.
Caps for Sale, Slobodkina: another classic. Depending on how much animation you read it with, kids can be rolling on the floor.
Pickle Things, Marc Brown: out of print for years, I find this crazy book far superior to his work with "Arthur."
Henry's Awful Mistake, Quackenbush: also out of print, but easier to get used copies of. A lesson in keeping your temper.
Sheep in a Jeep, Shaw & Apple: a quick, rhyming read about some very silly sheep. Sequels abound here, too.
Is It Time?, Janovitz: a book about a very cute wolf cub as he takes his bath, brushes his teeth, etc. Rhyming.
A Pie Went By, Dunn & Santoro: King Bing wants Queen Bee to marry him, so he bakes her a cherry pie and carries it on his head. The animals conspire to get him to fall down so that they can eat it. Very silly.
God Bless the Gargoyles, Pilkey: this book about God's unconditional love for us holds unusual emotional resonance.