While I believe Starbound is the superior of the two, Terraria is one powerhouse of a game I have sunk a ton of hours into. A lovely combination of Minecraft and Castlevania that has made it a classic for the annals of gaming history. A must have for anyone who enjoys pixel games/exploration games/crafting games/procedurally generated games.

And yes, I'm also shamelessly plugging my Youtube music channel, full of mostly game remixes. :P
https://www.youtube.com/user/Mozzaratti/videos