I would get the Ultra Maxx because of the RAM, camera, & larger screen. But to me money would not be a consideration. I have a Maxx HD now and like having a SD card but as it turns out so far the built in memory would be enough for me.
So, if the $200 difference is a big obstacle, the Maxx HD should be your choice. But if you don't require the extra memory capacity that the SD card provides and the cost doesn't matter, the upcoming Ultra Maxx should be your choice.
Good luck, whatever you decide,