I think Star Citizen looks more interesting... but it also has a lot of hype to live up to/lots of development time left.
Both look like they wouldn't leave time for anything else though. I've already got a backlog of single player games I'd like to get through before even trying anything on that scale. I just recently finished Bioshock Infinite, which was pretty cool... even if some elements of the setting were a clusterfuck of a mess. Cities:Skyline is supposed to be pretty damn good, too, if you want a true successor to the SimCity games.
Star citizen: You can play the same 2 maps forever with your pay to win ships while RSI spends the next 20 years laughing to the bank trying to make the game with your 40 billon dollars
Elite Dangerous: New shit monthly, a game you can play RIGHT NOW, and have a blast doing it. Leave your mark on the entire galaxy, going anywhere you can reach if your heart desires. Zero P2W aspects, in fact even hooking up brohams that come in is tough (but doable). Oh, and a one time fee for the game, playable either solo, as a group of friends, or online which is where I reside as a rule.