The question is... which one to get?
I didn't have the money for both X and Y and I don't think I'll have the money for both of these.
I don't know which one to get!!
Since they would both have all 700 something odd pokemon as a capability to hold, and I'm sure the new 2 will be in 3d as well, I would advise something simple: Look up to see if there are any known download events planned, when the time comes to purchase one. Usually it's the newest game that gets the download events, but since the Ruby/Sapphire are a "remake", they may get the short end of the stick.
X and Y would definitely have more of the "newer, so more than likely rarer" legendaries. Since there haven't been as many games with them for people to collect from. My two cents, at least. If nothing else, you could always wait a bit to see if they announce if it actually is a remake, or a sequel to those games, then go from there. At that point they would reveal at least a good chunk of the features, then you could decide which game has the features you desire more.