I have used as fine as 100 wt .............. and only as coarse as 35 wt.
If you want your stitches to pop a little, coarser thread will help do the trick.
Keep in mind, that any quilting "flaws" will show up better too.
If you want your stitches to disappear more, the finer the better.
Similarly, the finer thread will help any quilting mistakes be a little less noticeable.
Likewise, colour can make a difference.
A contrasting thread will help your stitches show more. Also, an stitching issues!
Meanwhile a matched thread colour, will not be as noticeable, helping to hide any imperfections.