Dragonblade
Adventurer
I gave look overs of books from all of the mentioned editions, especially BECMI, which was my original favorite choice (bought a Rules Cyclopedia as well, which I've since sold for what I had in it, $50... it was mint too). I actually played a few games of BECMI and enjoyed it, but really didn't like the limitations on some classes at early levels, nor the lack of limit on them later on.
PF Core Rulebook I just read, and read, and read, and read, and read and... I felt like I would never be able to master that to the level I would like in a reasonable time frame, and also knew that my son (presently 10) wouldn't want to have to read such a vast amount of complex info to learn it for not only playing our games, but ultimately DMing for his friends.
4E... loved that the classes were each more capable starting out, and none seemed to rule the roost at later levels. Loved the relatively simple, and sensible rules. Loved that I could more easily grasp how to create adventures / encounters with the levels and creatures and whatnot. I could definitely see my son being able to handle this. Loved the monster tokens... totally solved the issue of not having any kind of budget for minis. Loved that I could get the Essentials books and kits, plus a battle grid, for about $130 and have everything we needed to go from then on, with anything else being supplemental that's awesome, but not necessary to have... though I spent every $ of Christmas money on Core hardcovers... just wanted it to satisfy curiosity and round out some fluff and settings.
Awesome! A friend of mine plays with his kids too and he loves 4e. Its very kid friendly. My son is only 1 so he is still too young to play.
Pathfinder has its strengths, I play both it and 4e, but I definitely prefer 4e for many reasons, especially its balanced class structure, ease of prep and encounter design, and so on.
I think the Essentials book are needed, but I prefer the original 4e core myself. I like to have more complex class options and find Essentials a little too streamlined for myself. But its perfect for kids to be sure.
I only wish that WotC had released Essentials in a single standalone book ala the classic BECMI Rules Cyclopedia (which I also own by the way). With larger pages and a smaller font, you could fit both "Heroes of..." books (since a lot of content is duplicated), the DM Kit book, and the Rules Compendium content all in one hardcover for say $29.95 or $34.95. Though I wouldn't go much higher than that in price.
Then sell Monster Vault and the tile sets separately. So really each player only needs one product, and the DM only needs two (the core book and Monster Vault, tiles are always optional since you can play with a battlemat).
But I'm not WotC. Apparently their marketing guys felt like having ten(?!) different Essentials oriented starter products, including 4 directed at players, would be an easier sell...