The One X+ is slated to come out Q4,
Has a slightly better camera sensor than the one the HOX (HTC One X) is using now (which it, and the SGSIII both use). It will also have 64GB of storage compared to the 16/32 of the Tegra 3 X/ International XL (which is the North American X), and will be using the MSM8960Pro Qualcomm Snapdragon S4 @ 1.7GHz rather than the MSM8660 @ 1.5GHz found in the One X and SGSIII currently (for North American One X's/International XL's). It will also come natively with Jelly Bean (and with it's release we'll also see the regular One series get its jelly bean updates)
Right now, the choice is really this... You want a better screen, go for the HOX; you want more storage, go for the SGSIII. They're still the top phones in the Android domain.
If Windows Phone 8 is your thing, the Lumia 920 and the HTC 8X are your main choices these.