Yeah the comparison between Minecraft and Terraria is kinda dumb and definitely growing old. They are both sandbox games with a pixel art style that came out around the same time and Terraria does have some survival elements, but that’s where most similarities end. They are very different games with very different goals which is why it’s so dumb to compare them based on gameplay or the number of items, weapons, enemies, biomes, bosses, etc. To make an obvious analogy, it’s like trying to compare apples and oranges. They are both fruits but they each have different flavors and textures that different people prefer or equally enjoy. Comparing the games based on content and gameplay is redundant because each player has their own person preferences.
Now with all that being said I do think there is one valid objective comparison between the games and that is the quality of each game. Re-Logic has made a very polished game and in each updated have added items, enemies, biomes, and features that are well thought out and add to the game in a meaningful way. They also intently listen to community feedback while not letting it influence what is best for the game.
Mojang on the other hand has recently been adding features that add little to nothing to the game instead of fixing/improving what is severely broken. In past updates like the Update Aquatic and Nether Update they somewhat succeeded in making meaningful changes but recently they’ve really lost their touch. They also promise to add underdeveloped ideas in the Minecon Votes that almost always turn out half-baked. You can’t fully trust players to make decisions that are good for the game.
But I think Mojang’s biggest problem and what REALLY brings down the quality of Minecraft is how they limit what they can do with arbitrary rules. They don’t make certain changes that could improve the game because “it would go against Minecraft’s core principles.” Re-Logic is willing to make big changes that might greatly alter the gameplay experience or go against what they think the game should be to improve the game's quality. For example in 1.4.4 they got rid of Mud drying out due to infection even though Redigit originally wanted the Jungle to be permanently damaged by Corruption. Mojang on the other hand won’t even add small things like hostile animals, tools that break multiple blocks at once, or more detailed building blocks like sideways slabs because of irrational rules found in their secret book of design guidelines. Design guidelines are good but they can easily be taken to far.
The TLDR is that the only thing that makes Terraria objectively better then Minecraft doesn't come from the bosses, enemies, weapons, building materials, the number of items, or gameplay. It’s the quality of each game and how each team of devs adds to their game, implement community ideas, and approach game-changing features. I love Minecraft and still enjoy playing it with my friends but Terraria is just leagues ahead when it comes to how much more polished and balanced the game is.