As always, my family will be getting both. Even three is possible. I'll get Omega Ruby for myself, while my wife gets Alpha Sapphire, and this holiday we're getting our daughter a 2DS, so she may just hop on the bandwagon as well, and get a second copy of Alpha Sapphire.
I'll be getting AlphaSaphire, because
Kyogre > Groudon
Blue > Red
And I still have my copy of Ruby (although I'm looking for a copy of Emerald...)
But, as I do with all Pokemon games, eventually I'll own both versions.
Read my username, then come back to this message. Mmhmm.
In all seriousness, I always thought Sapphire to be better overall. The only version exclusive that I like from Ruby is Zangoose anyway. Still, I really, really would like to own both versions. If the gracious gods up above dare to glance at me in my poverty, I hope that one will shed a silver tear for me, so I can pawn that and get the money for both.
I'll get Alpha Sapphire. I've already played Ruby and Emerald (my first games *sheds a tear*) , but I never got to play Sapphire. Also, I prefer Kyogre over Groudon. Sheer Cold is a hell of an attack, and I love the Drizzle ability. Your Water attacks get 50% more power AND you get STAB because Kyogre is a Water-type. Groudon just gets the extra 50% power for its Fire attacks thanks to its Drought, but it won't get STAB.
Also, I think it looks cool ;P
Truth be told I missed out on the later generations. I originally played Red. Skipped out on Yellow. Did play Gold since a friend of mine let me borrow it. Ruby/Sapphire was an entry I did not buy, reason being is that I didn't grow up in the luxury of buying every new entry growing up. As soon as I got my own stable job I bought the remake Fire-Red and Soul Silver. So definitely I'm intrigued to buy Alpha Sapphire to see what I missed ^_^.
Soooooooooooooooooo, I've started a trend in my pair buying, where I buy the one of the pair which's name's first of the pair, (X, HeartGold, FireRed, Diamond, etc.) So I'll go with Omega Ruby first. The only Hoenn game I've played is Emerald, seeing as though I was born the year that Ruby/Sapphire came out, and the Emerald copy isn't even legitimate, so I need to get ONE on release date. I will get Alpha Sapphire for Christmas, but seeing how fast X's storyline went, and I was wayyyyyy past finished by Christmas, when I got Y, I will do an Alpha Sapphire Nuzlocke. It's stupid to not do Omega Ruby Nuzlocke, I know. I will eventually do a -Locke on it, though. It's likely I'll download Omega Ruby, so I don't have the stupid issues with the Friend List and all.
I'm probably going to get Omega Ruby, since Ruby was my first game, but that might change if there's any significant reason to buy Alpha Sapphire instead. I'll decide when more about them has been revealed.