Those are the boards I'd look at in the Giga range with your allotted budget; I included the XP SLI as a reference point. The Gaming 7 has a niceties over the Ultra but they're both very similar in OC potential and support for higher-range memory. Basically, they're mostly similar in the 'gaming' range excepting the G1 but have a sliding scale of features. The OC potential is good from the Gaming 3 on up but 3 and 5 cost too much IMO when the 7 has better features for not that much more.
From other manufacturers, I'd look at MSI's Z170A Gaming M7 or the Asrock Fatal1ty Z170 Gaming K6. Depending on the features you want the ASUS Z170-A is pretty good and should have an easier time with your RAM, but in every other respect is mostly a sidegrade.