I'd like to make a Minecraft-like game and have zero programming experience. I've researched game engines quite a bit and know a few things I need, but also have some concerns I can't find sound answers to myself.
What I need:
A complete game engine, not a render/physics/etc engine.
Little to no programing needed. Scripting such as LUA is far preferable to C#.
Easy asset manipulation. (I don't know how to animate or really even model so placeholders will be in use for a long time.)
Up to this point, Unity has seemed like a prime target.
My main concern is this.
I want a Minecraft-like game.
Something the user can modify, something that efficiently stores and alters a huge world.
It doesn't have to be totally infinite, minecraft isn't, but I am going for procedurally generated and continually added to.
Is Unity my best bet? Are there engines out there made for Minecraft clones?
My time is limited so avoiding dead ends and generating results will help me stay motivated.
As has been pointed out: "zero programming expierience" and "time is limited" will kill any game dev aspiration, even a pac man clone.
What you seem to aspire to is much more complicated than that. So first you should a) be aware that there is no tool out there that will create a complete game without coding needed apart from simple cookie cutter games, and b) any game project you start will take a considerable amount of time if you do it as a hobby and especially alone, AND you have zero expierience making games.
You can bet that Minecraft was built in a lot of late hours and nights without sleep, so time really shouldn't be limited if you have such lofty aspirations.
Be aware that you will need 3 things in some quantities to achieve a success with such a project: Time, Money and Skill.
If you have more Skill, you can do more in less Time.
If you have the Money, you can buy the Skill of others.
If you have Time, you can develop the needed skills and you don't need the Money to pay others.
But lets end this here and move on to your main topic:
I don't know how familiar you are with the technical terms involved with "Minecraft-like Games". What you are looking for is a Voxel Engine. Now, thanks to the success of minecraft there are now multiple special voxel engines out there that might be very much capabel of achieving that Minecraft like look with little changing on your side - grphically. Some of them are even free or open source...
but: Only because an engine is free and some demo games made in it look good does not make it a good choice. The most important part of an engine, especially for non programmers, is the editor. And this part, more often than not, gets overlooked by the developers of free engines.
Another option are third party modules for the big engines like UE4 or Unity. For Unity, there are multiple Voxel Terrain solutions you can buy for little money from the Asset Store.
Of course, most of them are made for a more traditional, non-blocky terrain design. Yes, Voxel Engines don't have to be blocky, that is just the cheapest and easiest way to go with voxels (and the fact the minecraft developer was no artist AFAIK made this choice easier for him to design stuff for his new game, I guess).
I would guess most developers of these Voxel Packages would be quite open to making their Assets work with blocky terrain, and some might already do it (guess you are one in a big queue of guys that want to create "Minecraft, but better").
I know about C4 but I have never used it. It uses a Voxel Terrain Engine, thus might have the Voxel capabilities you will have to buy with Unity built in. BUT: AFAIK C4 is very code centric. As a non-programmer, you will most probably suffer because of this. An editor centric engine like Unity might be more to your liking.
EDIT:
forgot something I wanted to mention earlier.
You will be able to find engines that make the development of the client and graphics easy. These Engines might even have the needed Editor to shield you from programming for the most part.
But the biggest problem for you will be the networking part. The amount of engines with a networking layer built in that is powerful enough for a real MMO is limited.
Then there will be the need for a server. Here, its 99% Programming. I don't think you will find a server that will satisfy your needs completly.
Depending on how much you want to compromise you can go with a third party solution (Raknet, Smartfox, ...). Just be aware that, AFAIK these solutions have been developed for smaller Multiplayer games with a lightweight network layer.
You WILL find MMOs that use such solutions for their backend part, but you can bet, somebody HAD to write an extensive codebase to make a server part for it (and work around the limitations of these frameworks)