Half Grown Pumpkin Stem.

Cobblestone is a very common block, as stone is seen almost everywhere in Minecraft. Cobblestone is a popular stone to use in builds, as it is so easily obtained. Cobblestone can be used to craft stone slabs, stone swords, axes, pickaxes and shovels. By MovieBoxPro
Glazed terracotta blocks are some of the most unique and beautiful in all of Minecraft. These blocks are colorful, have intricate designs, and come in so many varieties. The way terracotta can be used in builds is quite diverse. They are great options for flooring, walls, and decorations

All of them

I find that it depends on the Texture Pack/Shader I'm using. I tend to favor the blocks I find aesthetically pleasing, and that all depends on the texture. With my current Texture Pack/Shader, I am leaning towards Iron Blocks & Gold Blocks, because I love the way they shine & reflect light. Metallic sheen is irresistible!

When talking about Vanilla, I might have to go with the Command Block, seeing as it's the #1 most useful block.

Water and lava because you can made a lot funny mob traps,if you're a noob in redstone...

netherite

Spruce Logs

dirt....

Dark oak wood planks :)

Any log since you literally wouldn't be able to get most of the blocks in the game without it.

cake

Tiled Deepslate and Blackstone Bricks. Blackstone because it goes well with almost any theme. Nether hell-base? Goes with that. Futuristic End base? Goes with that. Overworld base? Goes with that. Deepslate is more of a toned down version of Blackstone, and works best for an underground or futuristic setting.

Diamond

I'll go with command_block...

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polished diorite

Smooth Quartz

It's not because I love the Nether, but I do love Nether Brick and Glowstone. :)

Netherite, structure block, glided blackstone amethyst

my favourite block is your mother's cheeks
(9x9 structure btw)

netherite stairs