Meh on splatbooks... 4E rather has too many feats and powers by now...
What I really want? Republish PHB1 with all errata! Yes, I know it's not going to happen, they thought about it but pulled it
I still think that the 4E PHB1 is a great book, but the rules are rushed and unpolished in so many places. Imagine we'd get all the AEDU classes polished and republished...
* the Rogue, but this time with the ability to use Dex for MBAs
* the Wizard, but with the 8 classic schools of magic; encounter and at-will spells are prepared per encounter
* the Fighter... clean up Combat Challenge to be easier to understand
* Warlord... fine as is?
* the Cleric, with real leader powers and a proper Str build
* the Paladin, with a fixed divine challenge and a proper Str build (uh, pattern), and Cha-based MBAs
* the Ranger... with a less annoying Quarry mechanic?
* the Warlock, as a full-blown Controller (maybe add the option to exchange Curse damage for debuffs?). Also, switch to A-shape Cha // Con or Int