As much as I would like to try the new edition without house rules, I have a couple bouncing around in my head that I'd like to at least playtest.

Action Points: still grant extra actions, but PCs will have the option to instead use them to reroll one check. This is mostly for those poor fools who miss with their daily. I liked this idea until I saw the kensei AP power that granted rerolls. In an effort to not steal the kensei's thunder I'd boost that ability to both grant an extra action AND reroll it once (which is maybe
too awesome?)

The half-elf extra power: make the extra at-will, at-will! It makes for a pretty sorry per-encounter power IMO, and seems to make the race less attractive. When I first saw the DDXP warlock with that sorry little Ray of Frost I assumed it was At-Will. Even then the player who tested the warlock barely used this power as it was kinda weak compared to Eldritch Blast and Eyebite. I don't see great balance issues arising from the extra At-Will power actually being At-Will, and it would give level 1 gish characters a decent race to pull it off.
Cosmetic changes:

"Kensei" will now be known as "weapon master". Unnecessary Japanese words are forbidden! Not that I have a problem with Japan, but I have had....words with a Japanophile player who constantly ripped off anime characters when creating PCs. He made Goku from DBZ, Orson from Lodoss War, and the main character from Bleach. All characters looked and acted like their anime equivalent, with only minor spelling changes to their names. I need to stop him from making Narutou before it's too late!

Dragonborn females will NOT have breasts. In fact, they will look and sound exactly like male dragonborn. Only other dragonborn will be able to easily tell their genders. I'm making this change because, well, it sounds like fun (especially when the scaly overmuscled tank with the huge greataxe and the booming voice reveals its name is the draconic equivalent of Susan). Tails will be back too.

Tieflings won't ALL have the exact same demon features. This is a request from one of my players who wants to play a tiefling with actual eyebrows, as well as less overstated horns. Demon features will likely be unique characteristics of individual tiefling clans (some bloodlines will have crazy big horns, some will have smaller tails, some will have red scaly skin, and so on) but all tieflings will still be recognizable as such.