Well,it depends mostly on what mainly catches your interest,so from my recommendation,I'd say to pick up Pokemon X/Y/OR/AS,Kid Icarus Urprising,The Legend of Zelda:A Link Between Worlds or Mario & Luigi Dream Team.
Pokemon X/Y/OR/AS are not really too different from each other,other than XY being a completly new Pokemon game,and ORAS being a revamped remake of Ruby and Sapphire,although,since it was released after XY,ORAS has more content than that game.I haven't played Omega Ruby or Alpha Sapphire yet,but I plan on picking them up sometime in the future,but I guess you would probaly want to get ORAS primaly for the new stuff in it,like new Mega Evolutions and stuff to do.XY is not a bad choice,though.
The Legend of Zelda:A Link Between Worlds is somewhat a new game and somewhat a remake of A Link to the Past,and although I haven't got a lot of progress in the game yet,is pretty creative and unique in it's way,and it really requires you to get thinking in order to progress in certain moments of the game.It's a Zelda game,so there's no question it's on the positive side of things.
Mario & Luigi Dream Team has a structure similar to past Mario & Luigi games,and it works greatly.On that,there's a wacky and fun concept with Luigi's dream interactions,hilarious humor and dialogue,great boss battles and awesome gameplay in general.
I haven't played a Kid Icarus Urprising yet,but I suppose it's just as great as the previously mentioned titles,and I did hear it has a great character cast throughout a well-developed story,so it's safe to say this should be a good pick as well.
Really,you won't regret your decision upon buying any of the games I mentioned,personally.