As much as I don't wanna recommend it for personal gripes, I'd say go with minecraft if you want more content in general due to the size of the fan base.

If you don't care as much and just wanna play a voxel sandbox game and don't care about having as big of a backlog of fan made content, Luanti ( formerly MineTest ) is a fine enough platform.

The drawbacks for mc, in my opinion, are pretty much things like chat verification ( assuming they actually went through with that ) for basically all messages you send, even in single player mode. And, assuming they didn't back down and did parity on java with the bedrock version that chat and signs are censored to make sure in every single way you play, either online or single player, is child friendly by replacing all characters with asterisks. I personally left over both of those because I prefer not being treated like a child and having parental controls forced on me.

Also, drawback for mc bedrock is how they, still, after years have bugs where you'll just randomly start taking damage or will be placing blocks that will not actually place, causing you to die from falling if you are high enough or other similar bugs. Works in single player, too, as far as I'm aware. Rubber banding kind of issues that I don't know if they've actually fixed yet. I'd hope they have, but I doubt it. There's a reason I've heard that version be called "bugrock" many times before in the past. Besides that, the bedrock version is also home to a marketplace where you have to use purchased in-game currency. Just something to keep in mind, despite it not being something you have to ever use. Also, that version doesn't have access to basically any of the mods the java version has.

The drawbacks with Luanti are the fact that there's a much more limited amount of content available in comparison to the behemoth mc. You have some games like VoxeLibre ( formerly MineClone2 ) and Age of Mending that are getting updated, but there are a lot more games not being updated because they're either already completed or abandoned. You'll also have some trial and error if you turn on a lot of mods for your save in any of the games because even if they say they'll work in a game because dependencies are met, you still might have mods that instantly crash your save and give you an error that they won't work for some reason or another. If you know lua you might be able to fix the errors, but do you really want to spend all that time fixing errors and getting a mod to work or would you rather just play without them? Same sort of problem, depending on the game, applies if you apply mods like Unified Inventory or any other Just Enough Items type inventory changing mods, like if you try on VoxeLibre. Haven't figured out how to get Unified Inventory to work on there.

On the subject of specific games, for VoxeLibre ( one of the games trying to be a Luanti parity of minecraft ), you'll probably be updates upon updates behind minecraft for a really long time or until the devs either quit or are forced to quit by macrohard/mojangles sending a cease and desist letter or something similar. Features that work just fine on mc, like redstone, might be buggy or don't work the exact same on voxelibre. For example, due to differences in TNT explosion physics ( I assume ), TNT cannons don't work despite the redstone for basic ones working just fine. Also, as a fault of Luanti in general, if you look in controls, your "Aux1" key is the sprint key in voxelibre, but absolutely nothing tells you that.