Below is a list of all the English language G1 MLP books that I know about, not including variations:-
Adventure Book
Annual (1984/85)
Annual 1986
Annual 1987
Annual 1988
Annual 1989
Annual 1990
Annual 1991
Annual 1992
Annual 1993
Annual 1994
Baby Firefly's Adventure and other MLP Stories
Baby Lucky and the Bewitched Basket (mini activity storybook)
Baby Quackers and the Sad Quolly
The Big My Little Pony Storybook
My Little Pony and the Birthday Wishes
A Book of Favorite Things to Touch and Feel *
My Little Pony at the Country Fair *
The Cross Weather Witch
Dance and Prance
The Dance Recital *
Dancing Butterflies and the Bad-tempered Butterfly
BHS MLP Storybook (The Runaway Rainbow)
BHS MLP Storybook (#2)
Favourite Stories
Fun in Ponyland
Glory, the Magic Unicorn
The Grand Pony Parade
Gusty and the Genie
My little Pony Learns to Count
Lickety-Split and the Wood Sprites
The Little Ponies and the Pixie Sea Pirates
Lost in the Clouds
The Magic Nut Tree
The Magic Rainbow
The Magical Music Box
My Little Pony Makes a Wish *
The Man in the Moon
My Little Pony and the Mystery Chase
My Little Pony and the New Friends
The Night Before Christmas *
Party Time at Dream Castle *
Picnic at Paradise Estate
The Picnic Party *
Playschool Pantomime
Pony Parade
A Problem for the Baby Ponies
Rainbow Rider's Birthday Adventure
Round and Round
The Sea Ponies Live in the Sea *
Sea Ponies Water Fun
A Shock at the Stable Show
The Snow Storm *
The Sparkling Show Stable Show
Spike and the Magic Shoes
Spike, the Babysitter (mini activity storybook)
The Stable Show
The Stolen Shadow
My Little Pony: The Storybook of The Film
Strange Times in Pony Land
Surfdancer and the Little Mermaid
Sweet Dreams
The Trolls and the Castle of Darkness
Under the Big Top!
Where is Cuddles?: A Book of Hidden Surprises
(Untitled bathbook, green, 1991) *
Also, if anyone knows of any others or has any of the ones marked with a * for sale (or any not listed) please let me know!
My favourites include the first annual and Where is Cuddles?