Question: Should I make a Minecraft-inspired game in 3D or 2D?

Do whichever you prefer.

Don't try to base it on imagined critical acclaim or market forces, what you are doing does not have a significant market. There are many thousand hobby Minecraft clones, plus major professionally made clones and voxel games. You would not be asking if you had already done the research for a data driven decision.

Since it is you doing it yourself for your own sake, pick whatever satisfies your own desires for the game.

A 3D minecraft clone was my first real game project back in the day. I made that in OpenGL (1.1, so it ran horribly slow). Programming-wise, it's not that complicated to make a 3D minecraft-like game. It's definitely doable. So I don't think that disqualifies the 3D choice on the basis of effort required.

aquariumdev said:
I want to understand which option is more accepted in the market nowadays and which one has a better chance of becoming popular.

I don't think you're asking from the right perspective, and I agree with frob, you probably won't get either attention or money from that. And given how you also don't seem to understand (or at least mention) the implications of the difference between a 2D vs. 3D game, it seems to me that you also aren't in it because you actually want to make something specific, but rather, because you want to do what everyone else did. That's not how you make it good. Only through great luck and by accident can you make something good by simply imitating the form.

Now, 2D minecraft-like games such as terraria have completely different constraints and look-and-feel compared to 3D games. First of all, line of sight: In a 2D game, you aren't really restricted by walls, you can see everything that's on screen (if it is well-lit). In a 3D game, line of sight and 3D aim matters, while in 2D, you just click at something with the cursor, and the movement of the cursor does not rotate the camera. This alone already makes a huge difference in what kind of mechanics you can put into your game, and therefore, the potential fun a game can have.

If you don't have an idea beyond “harvestable block world with crafting and some mobs”, then do NOT approach it with the intent of gaining any attention or money or even any reaction at all. It is still a valuable thing to have under your belt, I think, to be able to make such a game on a technical level, so I don't want to entirely discourage you from that project, either.

If you actually want to make something for which marketability is relevant, I recommend doing something entirely different. A small game that has low production cost, but does something unique, and does it really well. That's how all the indie games that were successful recently did it. It doesn't even have to have graphics (see Warsim for example, which managed to really leverage the little it has, and has carved out a niche for itself). And other notable indie games that had greater scope / production value were great because someone really, really poured a lot of love into it, regardless of time and cost spent on it. But if someone were to clone those, even with higher budget, it would probably end up in failure, just like many sequels to legendary titles really sucked, because they thought they could just copy the general form of the game, without actually having the passion and inspiration that went into the first game. More important than the form of the game, IMO, is the inspiration, love, and dedication that goes into it. And those legendary titles still hold up today, maybe not visually, but they are still masterpieces because even though they had to make do with little, they used everything to their advantage to form a cohesive whole.

Unless you actually have inspiration on that level, I recommend that you do not even think about profit, marketing, etc. Just make a few toy projects, clone a few well-established games if you can't find inspiration, and polish them to the best of your ability. Maybe an old arcade game or two per year, rebuild it yourself and make it high quality, and maybe also add your personal spin to it, but don't force it, either. That way, at least you get practice and experience and insight. And the market is not like it was 15 years ago, where there basically weren't any indie games. Everyone can now pump out a buggy AI slop knock-off, and that's what everyone did, and now even the flash games / HTML5 games sites are full of terribly bland garbage. Making something good is what sells, and making it good takes great care and inspiration, which I honestly you do not have with that idea of yours right now. You have to fail often to calibrate your imagination and intuition. Don't think you can make it before you have been at it with passion for a long time, and failed often. That's the rarest of cases, that someone makes something great without having failed often before.