Of all the leveling systems out there, I prefer Guided Reading. I just feel like GR is slightly more accurate because it takes multiple factors into account, not just sentence complexity and vocabulary, but also content, theme, etc.
After completing Teach Your Child to Read in 100 Easy Lessons, a child can read vocabulary that is considered 2nd Grade, based on the Fry Word List. However, I would say that it is more accurate to say that a child can read at a 1st grade level (GR levels E through J) because this is their independent level.
Wanting to provide my daughter with some more E through J books, I went on a used book shopping spree last night. Here is what I chose, along with some E-J (1st grade books) we already have:
Dear Dragon (E - all the Dear Dragon books are level E, we have I Love You, I love it, found more)
Inside Outside Upside Down (E)
Each Peach Pear Plum (G)
The Carrot Seed (G - we have it)
Dinosaur Roar (H - we have it)
Big Red Barn (H - we have it)
Goodnight Moon (H - we have it, who doesn't?)
Put Me In The Zoo (H)
Old Hat New Hat (H)
Quick As A Cricket (I - we already have it, great for teaching similes, a must have)
Small Pig (I - author Arnold Lobel)
Curious George's Opposites (J)
Great Day For Up (J)
I Can Read With My Eyes Shut (J)
Cat in the Hat (J - we already have it)
Green Eggs and Ham (J - have it)
Hop on Pop (J - have it)
I will not be buying a book called Mine's the Best (recommended by TYCTR) because it uses the phrase "I hate..." and I don't want my three year old using that phrase.