Join or boolean Union

Hello,
I would like do a mesh with a cylinder and a cube.
What is the best solution used join or used a boolean union or used another solution? (render, …)
I join 2 example:



the left is the boolean and the right is the join.
If the join is the best solution, is it important that the face of the cylinder are exactly on the cylinder face? and is it necessary to delete the bottom face of the cylinder.

And an other question.
To extrude a cylinder from a cube the boolean extrusion is the best way?


Thanks in advance for helping me.
Cyanim

is it important that the face of the cylinder are exactly on the cylinder face?

It is best for the object to intersect some what.

To extrude a cylinder from a cube the boolean extrusion is the best way?

What do you mean by best way? What problem are you seeing?

you can make a cube then in edit mode shift A and add a cylinder, it basically does the same thing as join, however for what you want the best way would be to make the face of the cube that you want to have a cylinder come out of have this sort of geometry,



Use the mirror modifier so you only have to deal with 1 quarter of the cube’s geometry
Edit: I should mention to get the circle perfectly round like that the easiest way I’ve found is to enable to edge loop tools add on and use the relax tool, this was i think 10 iterations or you can click it multiple times. But this method keeps it all quads and if you’re planning on using subsurf modifier it prevents various problems.

Sorry i did an error I would like to tell on the cube face.
is it important that the face of the cylinder are exactly on the cube face?

Best way = in the aim to optimize the render time, because i will have a lot of cylinders above cubes and a lot of cubes extruded by a cylinders

Using my example you will be able to do both those things and avoid shading issues that might come from boolean,Cubes.blend (513 KB)

Thank you !!!