I think Terraria better than Minecraft because terrarias 1.3 update came out so now there is more items and bosses. Minecraft has only 2 bosses that I know of and Terraria has like 15 on pc so... Also minecraft Isn't Infinite either there is a end to the world if you telaport to 32,000,000 X and Y and terraria you know theres an end to the game. Terraria has more exploration than minecraft and theres chest all around the world and there even events that happen.
While Minecraft's base game might not be as fun as Terraria's that isn't where its real strength lies. The real fun of Minecraft is in its community with the unlimited creativity of the players letting almost everyone have something they can enjoy. As well as if you think the vanilla game is boring there is a massive modding community with a mod for almost anything.
Terraria has way better graphics than minecraft and is on more consoles like 3DS/pc/phone/xbox. Also minecraft I think is a remake of terraria. Minecraft might be bigger but when you beat all the bosses there is nothing else you can do because you already beat the game. In terraria there is more bosses and when you beat the game you can beat any boss in the game over again and again. Also you can get every item in the game easily in Minecraft but terraria makes you work harder for all the items like beating the game in expert mode and beating all the bosses over and over again to get the items.
While Terraria's 8-bit graphics are nostalgic and quite pretty you can't say that 8-bit graphics are far superior to the 16-bit graphics of Minecraft, not to mention how thanks to texture packs you can change the game to look however you want it to. Also while the vanilla endgame doesn't have much in the way of bosses there is still a lot you can do such as building a city or creating multiple houses and linking through the nether. As well as If you're after bosses you can download any number of mods which add multitudes of bosses you can respawn, equipment, boss loot, new challenges, and endgame content. Unlike Terraria where the modding community is so small almost no one actually knows that you can mod it. Minecraft also is superior as a sandbox game due to how customizable it is. You can change just about everything from adding magic in, to adding new mobs and bosses, to revamping the nether and end, to adding guns and missiles, to adding space travel, to adding realistic chemistry, to adding customizable NPCs , and there's even a mod to change the world into a collection of floating islands instead of the traditional world.
Minecraft's superiority doesn't come from the base game. Instead it comes from the community and the massive amount that you can customize the game. Thanks to mods no matter what it is you want to do in the game it can be done with the right mods.